Catching killers is in the genes
She’s a super-sleuth who helps US authorities solve historical crimes using publicly available DNA data. Genetic genealogist CeCe Moore tells Rosie Kinchen how she does it.
In early 1997 a 19-year-old called Christopher Tapp was taken into the police station in Idaho Falls, in the US northwest, to be questioned about the rape and murder of his friend Angie Dodge.
The 18-year-old had been found dead in her flat six months earlier but police had made no progress on the case. When Tapp’s name cropped up tangentially in a separate case of sexual assault, they grilled him hard about Dodge.
He was subjected to 60 hours of interrogation, during which the officers threatened him with execution, put him through sham polygraph tests and fed him details about Dodge’s murder that only the killer would know, before falsely reporting that Tapp had volunteered the information himself.
At first Tapp denied any involvement in the killing; then he admitted, in a state of confusion, to playing a part — a confession he quickly retracted. He was charged with the murder and convicted, even though DNA from the scene did not match his own. The prosecution simply incorporated that into its story; Tapp had an accomplice, they claimed, and he was protecting the other man.
Tapp served 21 years in prison and would still have a criminal record today were it not for CeCe Moore, a self-taught sleuth and genealogy expert who has become an archangel of the wrongly convicted and a ray of hope for the families of victims whose cases have long gone cold. Moore, 52, a former actress who starred in adverts and once dressed up as Barbie for local fairs, is America’s foremost genetic genealogist, a field she has largely helped to create. She leads a team of three at a Virginia-based company called Parabon NanoLabs.
Between them, these women (the field is almost entirely female) have solved more than 150 criminal investigations since 2018 — an average of one a week, a record that eclipses even those of genealogy teams working within the FBI.
The only tool at Moore’s disposal is publicly available information held on websites where people upload the results of DNA tests done at home — a fast-growing sector. She can interpret these results more fluently than many scientists and has devised a methodology that one FBI agent has called “forensic wizardry”.
There’s a crucial difference between how police handle DNA and how Moore operates. When the police obtain a DNA sample, they usually try to find a direct match on official databases. By contrast, Moore uses DNA profiles on genealogy sites to identify people related to the source of crime-scene DNA.
Individuals who are related share segments of DNA: the more distant the relationship, the less DNA they share. We humans share about 50 per cent of our DNA with each parent; by the time we reach a third cousin (having great-great grandparents in common) we share, on average, only around 0.8 per cent DNA.
The amount of sharing is established by finding the sequence of hundreds of thousands of variable points scattered along the human genome, the complete set of DNA we carry. Moore builds up “genetic networks” to figure out the likely identity of the person at the crime scene. Think of it like drawing up a family tree; but rather than tracing the branches outwards, the aim is to identify the common seed. “It’s like a puzzle,” she tells me on the phone from her home — one she is very good at solving.
She took on her first criminal case in 2016 when she was asked by police in Washington state to look into the murder of Jay Cook, a 20-year-old from Canada whose body was found in 1987. He had set off in a van with his girlfriend, Tanya, who had been raped and also killed. Police had taken DNA from the scene but they had failed to make any progress for 30 years. Whoever the killer was, their DNA was not on any database checked by the police.
Yet it took Moore less than two hours to run a search on the DNA sample and solve the case. “When I saw the match list, I knew it was going to be very quick,” Moore says. There were two people at the top of the list who shared DNA with the suspect and their DNA was close enough to his to mean that they were second cousins. “That is the sweet spot, where you only have to go back to greatgrandparents to find the common ancestor,” Moore says.
To top it off, the two people didn’t share DNA with each other, which meant they were from different sides of the perpetrator’s family tree. This was a stroke of luck; you need to be able to piece together both sides of the family line in order to find the point where they meet. “If I could find out how those two connected, I would find him,” she explains.
The name she came up with was William Earl Talbott II, a truck driver who lived not far from where Cook’s body was found. Police officers took a sample of Talbott’s DNA and confirmed it matched the crime scene sample. His name had not come up in any of the police files. Moore says this is true in almost all of the criminal cases she works on. In 2019 Talbott received two life sentences for the murders after a unanimous guilty verdict from the jury but last month an appeals court overturned his conviction because a juror was found to have “actual bias” while being questioned during jury selection. No concerns were raised about genetic genealogy. Prosecutors were to review the ruling.
Moore stumbled across this field of work in 2009 after she had stopped acting and was running a production and casting agency with her husband. The home DNA-testing sector was in its infancy and Moore found herself working on an advertisement for FamilyTreeDNA, one of the early players. On set she met a genealogist called Katherine Borges, who showed her a trial version of a rival site called 23andMe, founded by Anne Wojcicki, then wife of the Google co-creator Sergey Brin. This new tool would allow users to access their “autosomal DNA” (the 22 chromosomes that do not determine sex) and track small genetic mutations.
Some 99.5 per cent of human DNA is the same from person to person, but there are small differences that make each person unique. These mutations, called single-nucleotide polymorphisms, or SNPs, combine to form unique patterns that are passed from one generation to the next. The 23andMe site offered a simple dashboard that compared users’ SNPs to make estimates about their relatedness to other users — whether they were first or second cousins, for example.
Moore was hooked. She called Borges, who ran the International Society of Genetic Genealogy, a volunteer body promoting DNA testing for genealogy, and told her that this was what she wanted to do with her life. Borges put her in charge of a forum for people who were new to genetics and interested in learning, and Moore immersed herself in the field. She began testing herself and her extended family, analysing their DNA and blogging about the results. At the time there was very little peerreviewed paperwork about SNPs and what these clusters of genetic “variants” actually showed in the context of human relationships and genealogy. This was where Moore focused her attention.
She started noticing anomalies: “Second cousins are supposed to share 3.125 per cent of their DNA on average, but some of my second cousins shared almost 6 per cent. Others shared 1 per cent,” she says. She was becoming expert at analysing such material.
At the same time public interest in home DNA testing was growing. By 2019 an estimated 26 million people had tested their own DNA. Most were interested in tracing family histories and this was where Moore set to work. She runs DNA Detectives, a Facebook group for people trying to solve their ancestral mysteries; it currently has about 170,000 members. She is particularly interested in “search angel” work, the term used by those who help adoptees and foundlings to track down their biological families.
It’s a strange new field of research; databases don’t offer you a sympathetic hug, so Moore has become an agony aunt of sorts. She often comes across a phenomenon she calls three-quarter siblings, in which a man has children with two different sisters, or a woman has children with two brothers. In these cases the children will share 37.5 per cent of their DNA rather than half. She gets about one email a week from people who have discovered that their parents are first-degree relatives.
Moore she says she was always aware that genetic genealogy data could also be used to solve crimes, but was very hesitant to start using it this way. “I knew it was possible but the question was what is the right way to do it so that it’s responsible and ethical.”
In 2014 she started having conversations with 23andMe to discuss the possibility of getting crime scene DNA into its databases. “They made it very clear to me that it was something they were not willing or planning to do.”
The turning point for many people, including Moore, was the arrest of the man known as the Golden State Killer in 2018. It was one of America’s most notorious cold cases: a man who had raped and murdered people across California in the late 1970s and early 1980s, and then suddenly stopped. Over 8000 potential suspects had been considered by the time the police arranged for a preserved sample of DNA from one of the crime scenes to be analysed using an autosomal SNP test; the results were uploaded to GedMatch, an open-source database where people can add their DNA profiles from other testing companies.
About 20 individuals who were potentially related to the Golden State Killer as third or fourth cousins were identified. It then took several thousands of hours of genealogical and other research to identify the most likely suspect, Joseph James DeAngelo. That gave police the lead they needed. They collected DNA from a discarded tissue and from the door handle of his car; conventional DNA profiling then provided a direct match to the crime scene material. DeAngelo was charged, and convicted of 13 murders.
For all the success of such genealogical detective work, there is one significant problem: it works only if sufficient people upload their information. Privacy concerns
around what DNA data may be used for could tip the scales against testing and put the field into reverse. Moore was expecting a backlash after DeAngelo was caught, but none came. “People were so positive about it, including some bioethicist academics that I have high regard for,” she says. “I sort of thought, ‘Well, gosh, what have I been waiting for?’”
The companies running the databases have been less enthusiastic. All except FamilyTreeDNA and GedMatch specifically ban law enforcement from using their information. Even GedMatch recently revised its terms so that its 1.5 million members worldwide would have to opt in to allow police to access the material. About half a million have done so.
The other obstacle is a technical one. Crime scene DNA is analysed in a different way to that collected by home testing kits. “It’s apples and oranges,” Moore says. So police have to rely on private companies, like Parabon, to convert crime scene material into the right format for genealogical researchers to use. They are also limited by the range of people uploading material; at present the vast majority are of Western European heritage. Parabon research shows genetic genealogy can be effective in a third of cases, and that they take on average 24 hours and cost £4000 (NZ$8000).
The field in Britain is smaller than in the US: the GedMatch database has about 150,000 UK profiles, but it’s growing fast. Two years ago Moore was able to find the biological family of a man called Steve Hydes who had been abandoned at Gatwick airport as an infant. He had been searching for his relatives for 15 years. “It was hard because we didn’t have that many UK testers,” Moore says. “But over time we’d get new matches and we kept
working.”
In Britain, genetic genealogy cannot currently be used in criminal justice cases, though last year the Biometrics and Forensics Ethics Group — an advisory body to the Home Office — published a report suggesting that “the initial use of the method in identifying otherwise unidentifiable bodies, would allow its potential to be tested in a UK setting, while avoiding some of the more contentious issues”.
Moore says some of the greatest potential lies in resolving miscarriage-of-justice cases such as that of Christopher Tapp in the US. By the time she was contacted by Idaho police to see if she could trace the semen sample found on Angie Dodge’s body, she already suspected that Tapp was innocent. By then the details of his interrogation were well known and even Dodge’s mother was campaigning for his release. “It made me even more driven to help solve that case, because I knew that Christopher was likely wrongfully convicted,” Moore says.
The genealogy was much harder this time around. Moore used the semen sample to create a DNA profile and a genetic map, which ultimately led the police to a man named Brian Dripps, who had lived across the street from Dodge and was questioned early on in the investigation. Officers retrieved a cigarette butt used by the suspect and confirmed that his DNA matched with the semen sample. He was brought in for questioning and confessed.
He had acted alone and had never met Tapp.
“It was the highlight of my career,” Moore says. “I’ve dealt with a lot of things that are really meaningful to me, but to be able to help exonerate Christopher Tapp is the thing I am most proud of.”
To be able to help exonerate Christopher Tapp is the thing I am most proud of.
CeCe Moore