The Algorithm

they're not telling you. After moving to Chicago when she was nineteen, Africa started escorting. In October, detectives found her strangled in the bathtub of an Indiana motel. I just think a lot of it, and I think it could have been prevented. Years earlier, journalist Thomas Hargrove had learned about the concept of linkage blindness. Most connected murders go unrecognized, and I kept that in the back of my mind.

And then when Hargrove discovered an FBI database that tracked homicides, it gave him an idea, could we teach a computer to identify connected cases to find serial killings? From my Heart Media and Tenderfoot TV, this is algorithm I'm ben Keebrick I mentioned in the last episode that Africa's case flipped what I knew about crime on its head this episode you'll see why. Let's jump back to my conversation with Thomas Hargrove. So, at what point in my um

you were saying that we shouldn't ignore her. Grove told me that back in two thousand four, when he was working as an investigative reporter in Washington, d C. He had come across a database with information about homicides all across the US. He wondered whether an algorithm could find patterns within that data and to text serial killers. Maybe it could even be used to detect active serial killers who had not yet been caught. I did not know

that such an algorithm was possible. I was going on faith. I did believe that it was important, and I did believe that it could save lives, but I didn't know that it would work. I begged my editors, let me try this. Let's do a project looking at murder, with the understanding that the actual goal is to see if we could create a computer program that would identify serial murder. But remember this was back in two thousand four, years before people were talking about things like machine learning or

the power of big data. Because Harder was on the cutting edge of these ideas, it was sometimes difficult to get other people to understand him or to take him serious. Lee My editors recognized that this could be something very cool, that this could make news, but it's hard to commit to a project you don't know upfront whether it's possible. Ultimately, his editors told him that trying to design an algorithm

sounded too risky. It's normal for story pitches, especially ambitious ones like this, to get rejected, but what's unusual is that Hargrove didn't give up For the next six years. He kept pitching the story six years, and he says that his editors always considered it but would end up assigning him to another safer story. Then, in two thousand ten, Hargrove got his big break. He had just published a

provocative piece called Saving Babies, exposing sudden infant death. Hargrove had analyzed data from Corners offices all across the US and found that many times when infant deaths were listed as sid's sudden infant death syndrome, the evidence actually showed that the infants had died of accidental cufifocations. Most of the time, babies don't die mysteriously. They die from avoidable

accidents and unsafe sleeping conditions. They got covered up because of what was intended to be a very kindly diagnosis called SIDS. That was meant to be a kindness to parents. There was a mistake. This project prompted a national conference to re examine infant death. It caused the creation of a sudden Infant Death monitoring system by the CDC. I mean,

it was tremendously successful. It had got rave attention. Finally, after six years, my stock was high enough in the newsroom that I was able to get them to look at murder. My editors that, okay, Tom, you've got a year. I could do a national reporting project looking at unsolved murder, with the understanding that what we were really about was to try to develop a statistical means to identify overlooked serial murder. Could we teach a computer to find serial killings?

After years of dreaming about making this algorithm, now Hargrove had this chance to try and make it work. Hargrove starting to design a computer program, one that could comb through the five hundred thousand supplemental homicide reports and find patterns between victims, patterns that might suggest the work of a serial killer. So what is an algorithm? These days? Algorithms dictate much of our digital lives. They determine what TV shows get suggested to us, post we see on Facebook,

what route our GPS takes us on. Often these algorithms are black boxes. We're not sure what data is being fed into them and how they're deciding what to spit back out. But at their core, algorithms aren't mysterious. They're not even really that complicated. Algorithms are just sets of instructions used to accomplish a specific task. You could say a cake recipe is an algorithm for baking a cake.

You wouldn't say that, but you could. But while following an algorithm might be simple, designing a whole new algorithm is trickier. It wasn't like Cargroove was just baking a cake from scratch. It was more like he was trying to invent a brand new dessert. What we were doing with the algorithm was the process literally of trial and error.

The ability to experiment with data was critical. If you're trying to come up with a new dessert, might experiment with ingredients until you come up with a combination that tastes good. Hargrove knew what ingredients he had to play with. That was the data from the supplemental homicide report, which listed the weapon that was used he was shot with a handgun, the time and location of the murder January, and the age, race, and sex of the victim. Victim

is a blackmail eighteen years old. But as he experimented with how an algorithm might sort through that data, Hargrove needed a way to check if he was on the right track. So we decided to test each new prototype of his algorithm to see if it could detect a known serial killer. We used as our test bed the forty eight victims of serial killer Gary Ridgeway, so called Green River Killer. He was convicted convicted in a court of law of murdering forty eight girls and women in

the Seattle area. The question was, we'd teach a computer a process that would tell us that something god awful happened in Seattle. At the time, Gary Ridgeway was thought to be the most prolific serial killer in America. Her group figured if he could create an algorithm that could detect Ridgeway. Maybe it would also detect other serial killers that had gone unrecognized. To motivate himself, Hargrove stuck up a picture of Gary Ridgeway in his office. It was

one of his booking photographs. He was glowering and looked like it was glowering at me. Under that picture, I typed the headline, what do serial victims look like? Statistically? For over two decades, Ridgeway had killed women and dumped their bodies along the Green River outside Seattle. In most cases, by the time anyone had discovered those corpses, they were already skeletal. Ridgeway has snuffed out does sense of lives. He'd killed women and girls with their own hopes and dreams.

But Hargrove needed to approach their deaths like the algorithm would, looking at their cases by their numbers, using only the data from the FBI's supplemental homicide reports. So what did ridgeways victims look like? Statistically? And more broadly, what do a serial killer's victims look like? To find out, I reached out to one of Hargrove's collaborators, Dr Mike A. Mott.

A Mott is a forensic psychology professor at Radford University, and he curates the world's largest database of serial killers and their victims. If you look at how serial killers are portrayed in movies or on TV, the stereotypes not really very consistent with with the back Are these also stereotypes that law enforcement might have when they're trying to decide could this murder possibly be a serial murder? Well,

law enforcement certainly has the same stereotypes. When we've done presentations to law enforcement groups and even clinical psychologists that are police psychologists, they're very surprised at the results. I'm talking to Professor Mike al Mott about what serial murders look like statistically, because statistical differences between serial killings and other homicides are the kind of signatures and algorithm could

use to detect a serial killer. Professor Amatt has built a database with information on thousands of serial killers, and he told me that there are many misconceptions about these killers, even within law enforcement and the true crime community. The stereotypes about the profile of a serial killer or pro file of the victims is not really very consistent with the facts. If we want to catch serial killers, we need to know who they really are in the reality

of their crimes. I want you to stop for a moment and try to conjure up a mental image of a typical serial killers victim. How old are they, what do they look like? Now, imagine all of the victims of a single killer. What would you guess they have in common with one another? If we look at the victims of serial killers, of the victims or women or forty nine or men, so there's not really much of

a difference there. One of the stereotypes about serial killers is that they have a type, you know, kinde of victim that they're going to kill. The most consistent profile we can have is really in the age category of who they're killing. About are going to kill people that are in the same age categories, so it's children, or its teens, or its adults or elderly. Serial Killers are less consistent when it comes to other attributes of their victims.

For example, only six kill victims there are all male or all female. And then if you look at race, for example, of serial killers only kill somebody of the same race. And while the stereotypical victim of a serial killer is white, actually a third of victims or people of color. For Gary Ridgeway, the serial killer that Hargrove picked as his test case, all his known victims were young women, but they were diverse in terms of race.

In an interview with an FBI agent, Ridgeway says he targeted prostitutes out of convenience, and studies show that there's actually been a dramatic rise in serial killers targeting sex workers. In the seventies, prostitutes are thought to have made up around six of the female victims of serial killers. By the two thousands, more than two thirds of women murdered by serial killers were sex workers. Many serial killings are sexual in nature. About one third of serial killers rape

at least one of their victims. Ridgeway told detectives he'd have sex with his victims before he strangled them, and when asked why he chose to choke all his victims, Ridgeway replied because that was more personal and more rewarding than shooting them. And compared to typical murderers, serial killers are more likely to use methods that are up close

and personal, like strangulation or bludgending. So if we're looking at victims in the US about were shot, were strangled were stabbed and ten percent were blugend and serial killers tend to be consistent in the method they used to kill. Amont says that two thirds of serial killers use only a single means to kill their victims. So what are the takeaways from a MOOTS data? Serial killers show some but not perfect consistency in terms of their victims age, race,

and sex, and also in their method of killing. But it turns out that there's one more thing that serial homicides tend to have in common, a property that would be crucial for hard Groves algorithm. We spent the summer of two thousand and ten finding at least the hundred procedures that crashed and burned. Does the presence of a serial killer increase the rated which women are murdered? No? Does it increase the rate of which women are murdered

through unusual means? No? And do you get any indications that you're getting closer? Yeah, So as we were progressing through the hundred and one things that don't work, we were starting to get closer. So um, the last thing was to look at what the clearance rate was for particular types of weapons. That term clearance rate refers to the percentage of cases that police end up arresting someone

for the crime. Hard Group realized that Ridgeway had gotten away with his murders for so long that they've been listed as unsolved in the database. So if you looked at killings in Seattle that matched his method, the number of cases police had cleared was much lower than expected. The presence of an active serial killer often destroys the

batting average for the local police department. They're able to solve most murders, but not that type of murder because there's a serial killer who's avoiding arrest hert group was making progress. He'd picked up the hint of a signal from Bridgeway in Seattle, but it wasn't enough to make the algorithm useful as a tool. He racked his brain trying to come up with a way to improve it. One day, near the end of the summer, he looked up at Ridgeway's mug shot and asked himself again, what

do a serial killers victims look like? Statistically? As he talked through the project one last time with his research assistant, Liz Lucas, an idea struck him. As I was taking Liz to the airport because she had to go home to defend her master's thesis. I told her that what might work, and we're gonna try this next is a

kind of cluster analysis. Instead of querying all of the data, we tried to assemble the data into smaller clusters according to the county where the murderer occurred, the gender of the victim, the method of killing, and at that time age group. Then we calculated what the clearance rate was for each cluster, how many of those murders were solved. Up until this point, he tried looking at the data for all the orders in Seattle. His new idea was

to further break down the data. Have the algorithm split up the homicides for each county into buckets of victims, and then rank these different buckets by the percentage of cases that were solved. And Hargrove wasn't just doing this for Seattle. He was doing this for data all across the US, and he was hoping that out of the thousands of clusters, Ridgeways Seattle killings would show up somewhere near the top of the list. Hargrove ran his new

algorithm and waited anxiously for the result. When we did that, the Green River killings jumped out plane as Day came in third place most of the time seventies seven percent of the time, and arrest is made when a woman is killed in the cluster where the Green River killings were grouped. The solution rate was less than and that was our key. We're looking for groups of similar murders

that have very low clearance rates. We had hundreds of results all over the country, highly suspicious clusters, and we started investigating them. Heart Grove was a static. It seemed like his algorithm might be working. It detected Gary Ridgeway, the Green River killer, but at the same time, he designed the algorithm to detect Ridgeway, and he kept tweaking it until he did. So maybe the algorithm had just detected Ridgeway by luck and it wouldn't generalize to other killers.

In statistics, this is a problem called overfitting, and it's a common problem when scientists try to make algorithms that predict things. So to get around this problem of overfitting, people often train their algorithms with one set of data and then validate the algorithm by testing it with new data. So, since Hargrove had been using homicides in Seattle. To train his algorithm, he needed to look at other cities to see if it was really working. There were two larger

suspicious clusters, and in first place was Los Angeles. They were a large group of almost entirely African American women who were killed by handguns, and those murders had a very low solution rate. So I assembled a spreadsheet of those murders and emailed them to the public relations department of the l a p D. Got one of the representatives on the phone, is there a chance that any of these could be serial murders? And he spent a minute or so looking through the files, and then he

can back and said, what are you kidding? They're all serial killings? I said, what. In fact, in the es l ap D established what they hoped would be a secret task force. They didn't want to alarm the public, but they were exploring the possibility that there could be a serial killer active. They called it the South Side Slayer Task Force. Well, it turned out that the task force was misnamed. It should have been called the South Side Slayers Task Force. Because they had five they were

all quite independent of each other. They didn't know each other but they were all killing women over a period of twenty years. You heard that right. During the eighties and nineties, Los Angeles had at least five different serial killers who were shooting, strangling, and sexually assaulting women in the area. This was happening at the height of the crack epidemic and at a time when homicides across the

US where peaking. The large number of overall homicides probably helped cover up the fact that there were these serial killers operating in l A. But it's also likely that the police didn't give these murders enough attention due to a phenomena that's sometimes called victim discounting, and this is the tendency to ignore crimes targeting marginalized groups. But when Hargrove found out about these l A serial killers, he took this as another sign that the algorithms seemed to

be working. It had detected a group of confirmed serial killers that he hadn't even been aware of. Hargrove continued down his list of top clusters that the algorithm had identified. He called up the police department in Youngstown, Ohio, and left a long message where he tried to explain the algorithm and how it had detected a cluster of murders in Youngstown. Thirty minutes later, the phone rings the chief of detectives and you gotta give him credit, answering a

voicemail like that, he's a young guy. He called back and said, that was the damnedest message I ever had on my phone. And so I went back and I interviewed my senior detectives and they told me something I did not know. We thought we had a serial killer in the nineties. We definitely thought we had one, and we never got him, and so we started a new investigation. He was attempting to locate the rape kids from those cases, to try to DNA type all of the rape kits

they could find. Unfortunately, and this was very embarrassing, the rape kits had all been destroyed, the property rooms had been cleaned out, and he was not able to get any of the kids from his cases or from surrounding jurisdictions. There were other similar murders in neighboring jurisdictions, but they too did not retain the rape kids. So it was it was very sad, but they gave it the old college try again. The algorithm had identified a cluster of murders that seemed like it was the work of a

serial killer. Police couldn't prove that the killings were connected, but the algorithms findings lined up with what police suspected, and the algorithm had inspired a reinvestigation of those cold cases. Hargrove felt like he was on the right track and that maybe the algorithm could be a useful tool for law enforcement. We selected ten major cities that appeared to have a suspicious number of algorithm identified murders. Gary was one of those ten. Gary, Indiana, the city right next

door to where Africa Hardy would be strangled. Four years later, the algorithm flagged fifteen all unsolved murders in the Gary, Indiana area. They were all women who were strangled. Not one of the cases were solved, which is unusual. Seventy seven percent of female murders get cleared, but not one

of these fifteen strangulation murder and Gary were cleared. I called the public relations officer for the Gary Police Department, gave him my name and said what we had found, and said, is there a chance that you're dealing with a serial killer? The next day the phone rings, it's uh as I recall His name was Captain Roberts, who said, UM, I've checked with our detectives and I can tell you definitively that there are no unsolved serial murders in Gary, Indiana,

which is by definition an impossible statement to make. Unless you have no unsolved murders, you cannot claim you'd be definitively certain that there are no unsolved serial murders. Hargrove felt like the police were just blowing him off, so he started investigating the fifteen murders himself. Hargrove wanted to know whether the algorithm was working, and he thought that if he found evidence suggesting the murders were connected, maybe the police would start take came seriously. But looking up

the information about the cases wasn't easy. The FBI supplemental homicide report didn't include the victim's names or even the exact date of their death. It just listed a month in a year. So define more details about the cases, Hargrove had to meticulously dig through old issues of local papers, and as he started to piece things together, he was

unsettled by what he found. He was disturbed not just by how grotesque these murders were, but by the patterns that seemed to link them, and he became convinced that Northwest Indiana had a serial killer on the loose, a strangler who was targeting young women, women just like Africa Hardy. He tried to talk to Gary's chief of police, but he couldn't get through. I continued to suggest, have you really looked at these cases? Soon the police stopped returning

his calls altogether, and Hargrove needed a response. He wasn't just playing arm chair detective. We were about to publish a story saying that Gary, Indiana has a serial killer and the police would not talk about it. We were afraid that the reason they weren't talking to us was because they were hot on the heels of solving it. That they had a suspect that we're trying to reel them in, and we were going to screw that up. We needn't have worried, but um, that was our fear.

I even sent registered letters to the chief of police and to the mayor saying what we were about to do, and if there's any issue they have, or any conversation they want to have, for heaven's sakes, call me. This is the letter that I wrote to the chief of Police and Mayor in Gary, Indiana, and it goes dear Chief. Carter Scripts Hour news service based in Washington, d C is conducting a national reporting project looking into the thousand

unsolved thomicides committed in the United States since night. As part of this project, we are investigating whether it's possible to spot victims of serial murder among these unsolved killings. Using the FBI's Supplementary Homicide Report. Using multivariate analysis, we've determined that Gary, Indiana has an elevated number of unsolved

murders of women who were strangled in recent years. The data that your department reported to the FBI are consistent with the possibility that multiple victim killers have operated in northwestern Indiana. Broadly, we see two possible patterns. In recent years, several women have been strangled in their homes. In at least two cases, of fire was set after the women

were killed. Also, starting in the nineteen nineties, we've seen several women who were found strangled in or near abandoned buildings. We doubt these killings are the result of convicted serial killer Eugene V. Brit who admitted to killing eight people. Please note the attached list of homicide victims. We'd be grateful if your detectives would review these cases to determine if any might have a common perpetrator. The US Justice Department defines a serial killer simply as anyone who kills

two or more people in separate incidents. Experience thomicide investigators tell us it's extremely difficult to spot a serial murderer. There have been enough unsolved killings of women in Gary, Indiana that your metropolitan area made our top ten list. We are contacting authorities in all ten areas. Police and five cities have already confirmed that cases we've cited contained

proven or suspected victims of serial murder. We are also making a similar request to the Lake County Coroner's office. Thank you for your time and consideration. Please help us explore whether national crime data can assist local law enforcement. Sincerely, Thomas Hargrove, Scripts Hour News service, and we had total

radio silence from those people. The Gary police chief and mayor didn't respond to Hargrove's letter or to his follow up phone calls, but Hargrove had also sent the letter to the county corners corners or the public officials who oversee autopsies and determined causes of death. They work with

the police, but they're an entirely separate entity. When I called the Lake County Coroner's Office, identified myself, I'm Tom Hargrove calling from Washington, d C. Oh just a minute, Mr Hargrove, the senior deputy corner, wants to talk to you. He came on and said, Mr Hargrove, we got your packet of information. Thank you very much for sending it. I'm assigning it to one of our assistant corners, a lady named Jackie. We're going to have her look into it.

An entirely different reception them when I didn't get it Gary, they agreed with us that there were too many unsolved murders. She added three more cases that she thought belonged on that pile we had identified fifteen. She added three, making eighteen that she thought were connected and was trying to have a conversation with the Carry Police department. She's never gone on Mike to talk about this case. For the Coroner's office, it is very, very difficult to speak ill

of a police department. It's considered bad form, and so she probably still feels a reluctance to do that. Although she has passion about this case, you shouldn't use this recording where I named her unless she agrees. I was looking up other names of people in that department, you know. I think one went down for some kind of corruption charge, and then it's kind of hard to find someone who is there that can talk about this stuff. Yeah, now your your only hope is to get Jackie to talk.

This is really one of the most frustrating experiences of my life. I think the Gary Police Department should be looking at some of those old cases. They still may have a killer out there. When I finished speaking with hard Grove, I tried calling Jackie, but I couldn't get through. After a couple of failed attempts, I left her a voicemail explaining the podcast how I was trying to look into the murders Hargrove had identified to see if they

were indeed connected to Africa's death. Weeks passed, and I've worked on other stories and chased down other leads, and after what Hargrove had told me about her reluctance to talk about the case, I didn't think she would want to speak to me. Then one morning I woke up to a missed call from a number I didn't recognize. Hey, Don, this is Jackie. You would try to contact me a while back in regard to heart Grow story you're doing. Yes, you want to give me a call later next week? Um,

that would be fine. Sorry, had gotten back to you sooner. It's just everything is fine, a little different. All right, guys, I'll talk to you soon. Maybe that's coming next episode. They don't want to talk about it either, I assume because they don't want to embarrass their neighboring police agency. All right, and said here and they had nothing to do. They led to the death your friend. You should try to find out. You'd be the first to do that.

Algorithm is released weekly on Tuesday's Subscribe Now so you don't miss the next episode on the I Heart Radio app, Apple Podcasts, or wherever you get your favorite shows. This episode was written and produced by me ben Key. Brick. Algorithm is executive produced by Alex Williams, Donald Albright, and Matt Frederick. Production assistance in mixing by Eric Quintana. The music is by Makeup and Vanity Set and Blue Dot Sessions.

Thanks to Christina Dana Miranda Hawkins. Jamie Albright, rema El Kaili, Trevor Young, and Josh Thane for their help and notes. Again, thanks for listening as it heads up. I'm still working on this podcast as we release it, so any feedback is appreciated. I think Algorithm is going to address some really important issues about policing and how crimes are investigated

that don't receive enough attention. So if you can, please leave a review on Apple Podcasts or tell a friend about Algorithm, where brand new show and could really use your help.