The “Y” That’s Helping to Crack Cold Cases Around the World

Recent headlines offer remarkable demonstrations of just how Thermo Fisher Scientific’s human identification tools are helping law enforcement agencies from South Los Angeles to Western China solve crimes, including some of the most brutal and confounding cases that remained unsolved for decades.

In August, Chinese state media announced that police arrested a 52-year-old man after DNA evidence identified him as the serial rapist and killer of 10 young women and an 8-year-old girl. The man, who had been eluding police for 28 years, had been dubbed “China’s Jack the Ripper” because of the similarities between his crimes and the notorious serial killer in London during the late 1800s.

Also in August, a former sanitation worker, dubbed the “Grim Sleeper,” was sentenced to death for murdering nine women and a teenage girl during a South Los Angeles crime spree dating back 30 years. Once again, DNA evidence led to his arrest. In both cases, Thermo Fisher’s chemistry was key to unlocking the crucial DNA evidence used to track the killers and confirm their identities.

DNA Evidence Collection

Thermo Fisher’s genetic analysis technology plays a key role in similar cases around the world, initially when investigators seek to extract DNA from crime scene evidence. Whether the evidence is human tissue, hair or bodily fluids, law enforcement laboratories often use our AmpFLSTR™ Identifiler™ PCR Amplification Kit for the job.

This solution is the single most widely used short tandem repeat (STR) based kit for human DNA identification applications. It allows DNA evidence to be analyzed in a way that is consistent with major worldwide criminal database standards. Once investigators have a DNA sample, it must be processed through a genetic sequencer to determine its unique genetic code.

Applied Biosystems first introduced the world to fully automated sequencing technology in 1987. Today, Thermo Fisher is the only company that provides approved instruments (3500xL, 3130, 3130xL and 310) for use with the network of databases that store the unique genetic profiles of people convicted of crimes throughout the United States and other select countries. In the U.S., the FBI has serviced this national network, called the Combined DNA Information System, or CODIS, since 1998.

Currently about 60 countries have some kind of criminal database, and collectively they store the genetic information of approximately 70 million people. Exactly when law enforcement can collect and store DNA, and how they can utilize the databases, is dictated by the laws of each jurisdiction and country. We work closely with many countries and jurisdictions to help them determine the best methods to work within local laws and use the best available tools to solve their cases.

After sequencing a case sample, forensic investigators then compare the DNA evidence to the genetic profiles in the databases. Law enforcement has used our AmpFLSTR™ Identifiler™ to search for exact genetic matches, as well as familial searches in which the evidence DNA matches many of the markers, but not all, indicating the records on file belong to a relative. This kind of information can help investigators narrow their search for a suspect.

In both the China and Los Angeles cases, the perpetrators’ DNA was compared to those on file in criminal databases. Initially, no match was found in either case. The cases grew cold until recently, when the DNA evidence in both cases was processed using Thermo Fisher’s gender-specific DNA analysis technology.

Y-Chromosome Identification

Only male DNA carries the Y-chromosome. It’s passed from father to son, and can be used to show a male familial relationship. For forensic labs, Y-chromosomal data can be helpful in deciphering evidence containing multiple people’s DNA, such as in a sexual assault case. While also helpful to identify missing persons and assess paternal relationship, Y-chromosomal data derived from Thermo Fisher’s new Yfiler™ and Yfiler™ Plus DNA Amplification Kit also proved valuable to crack the recent cases in China and South Los Angeles.

The man who had become known as “China’s Jack the Ripper” was tracked down after his uncle was arrested for an unrelated minor offense. Upon submitting his DNA, investigators determined via Y-chromosome data that he was related to the serial killer. Later, the authorities analyzed DNA samples from his male relatives and found an exact match.

When they questioned the man whose DNA matched samples from the Chinese “Ripper” case, he reportedly confessed to the crimes.

In the U.S., Y-chromosome data is accepted in CODIS. States have established their own rules for accessing this information, as recently reported by the LA Times.

In the Los Angeles case, detectives entered the Grim Sleeper’s DNA into the CODIS database in 2008, but found no match. Eighteen months later, investigators found data of a close relative had been entered into the database. Y-chromosome analysis showed that person had a familial relationship with the killer. It ultimately led police to Lonnie Franklin Jr., 63.

After investigators put Franklin under surveillance, an undercover police officer posing as a restaurant’s busboy obtained a sample of Franklin’s DNA from a plate and utensils he had used. Using Thermo Fisher’s AmpFLSTR™ Identifiler™, investigators confirmed Franklin was the killer.

Aside from the advanced chemistry and sequencing platforms that help solve cold cases, it’s important to note the crucial role databases play in helping to identify the perpetrators of such violent crimes. Without the ability to store these genetic profiles and screen them against cases samples recovered from crime scenes, many cases would go unsolved, and countless criminals would likely remain free around the world to perpetuate their violence against citizens.