How genetic genealogy helped nab a Detroit serial rapist
A Detroit man named Lionel Wells was sentenced last week for sexually assaulting five teenage girls between 2007 and 2014. He’s the latest perpetrator of a violent crime identified with the help of a relatively novel investigative technique called genetic genealogy.
Investigators had Wells’ DNA from the victims’ rape kits, and were able to connect the cases together. But the DNA didn’t match anyone in law enforcement databases.
So the Wayne County Prosecutor’s Office turned it over to Parabon NanoLabs, which does investigative genetic genealogy work for law enforcement agencies. They’ve been doing that sort of work for just a little over four years, according to CeCe Moore, Parabon’s chief genetic genealogist and a pioneer in the field. During that time, the lab has been able to help solve about 230 violent crimes all across the U.S. and Canada.
Moore said genetic genealogy is about “using DNA to learn more about a person's family history and genetic heritage.” She said the type of DNA analysis they do is different from what law enforcement has traditionally used. “That means we have to go back to the original biological evidence and reanalyze it from scratch using more advanced technology,” she said. “So instead of just looking at a handful of genetic markers, which is what has traditionally been done, we look at almost one million genetic markers across the genome.”
Moore has access to two public databases where people voluntarily upload their genomes, some of whom have explicitly agreed to share their data with law enforcement. She and her team then look for people who share significant amounts of DNA with the suspect. “And then we try to figure out how closely or distantly related these people are, depending on how much DNA they share,” she said.
“And we build their family trees. And when we build those family trees, we're looking for commonalities, overlaps, patterns within that family tree, trying to find people who share DNA with the suspect and have common ancestors in their family tree.”
But Moore noted that’s only one part of the work. Once she’s sketched out a tree of family relationships, “I turn away from the DNA very quickly and I move to public records,” she said. “So the vast majority of my time is spent researching in public records, building people's family trees, both backward and forward, backward to those common ancestors. And then I have to do reverse genealogy where I come forward and identify all of the descendants of those common ancestors.”
One aspect that was key to the Wells case was location data. Wells’ DNA pointed back to roots in Mississippi, and most of the family is still located there. But Moore was able to identify one branch that relocated to Detroit, so investigators focused their efforts there. When they did, they found one family member “whose addresses overlapped very well with the addresses where the crimes occurred,” Moore said.
“It [genetic genealogy] is an investigative tool more than it is a forensic science. So we're looking at who shares DNA with the suspect, but we're also looking at other aspects, just practical aspects, like who's living close to the crime?”
Using the information provided by Moore’s team, an investigator from the Wayne County Sexual Assault Kit Task Force was able to get a search warrant for Wells’ DNA. It matched the DNA from the rape kits. He was arrested in July 2021, seven years after he committed his last known sexual assault. He was convicted of the five rapes, and sentenced to five concurrent sentences of 25-50 years in prison.
Moore said that Wells’ case was resolved surprisingly quickly, given that cases involving African American suspects can be harder to build around genetic genealogy because that population is generally under-represented in DNA databases. But in this case, “things moved much more quickly because the vast majority of that family stayed in Mississippi,” she said. “So finding that one key person who left Mississippi and went north to Detroit really ended up being important. And because of that, we actually were able to provide a lead to investigators very quickly after we got that matched list. I would say this was a pretty unique case in that way.”
Moore stressed that “genetic genealogy is not something that's going to lead to someone directly being arrested or charged with a crime. It's not used in court as evidence. It is just a tip pointing law enforcement in the right direction.
“They have to investigate the person or persons that investigative genetic genealogy is pointing toward, and determine whether that really is a person of interest in the case. Is there other evidence tying them to the crime? And most importantly, they have to somehow get a DNA sample from that individual and compare it against their court-admissible DNA profile.”
Wayne County Prosecutor Kym Worthy emphasized the same thing. “It’s yet another tool that we use along with all the other traditional ways that we solve cases,” she said. In the Wells case, “We did not rush to judgment. We were very deliberate.”
However, Worthy is hopeful that genetic genealogy can help solve other serial rape cases where DNA evidence points to an unknown suspect. She said that her office has either submitted or plans to submit evidence from about a dozen other cases that are part of the Sexual Assault Kit Task Force. That initiative tested over 11,000 Detroit rape kits that went untested over a period of decades. More recently, it’s turned its attention to holding perpetrators accountable, with identifying serial offenders as a top priority. As of August 2021, the initiative had identified 826 suspected serial rapists.
But Worthy said her office is judicious about which cases it chooses for genetic genealogy testing, because it has limited grant funds and the process is expensive. “We were very, very deliberate in selecting the cases because we wanted to be able to use these funds to try to include as many cases as we could,” she said.
In a statement, Worthy said that Wells’ sentencing was “the result of a long process to bring justice to these then-teenage survivors. This would not have been possible without the extensive genetic genealogy process. It is my hope that since justice has prevailed today that now they can find some semblance of peace. Justice and peace are the least that they deserve.”
Moore echoed that sentiment. “When we see a conviction such as this one, and we read what he did, what the victims went through, I think that is when we do feel a bit of happiness,” she said. “It’s not a really happy job. But my team and I were really happy to see that he had been identified, and that these victims were getting justice.”
*Correction: An initial version of this story said a warrant for Wells' DNA was obtained by Detroit Police. It was actually obtained by an investigator from the Wayne County Sexual Assault Kit Task Force. The information has been corrected above.