A serial killer confessed to a cold case murder, but police say DNA helped them track down the real killer

A serial killer initially confessed to a cold case murder from 1983, but police in Texas say DNA helped them track down and arrest the actual killer after nearly four decades.

On March 17, 1983, a deputy saw a fire burning in a wooded area. There, he discovered the body of a white woman, later identified as Laura Marie Purchase, who was set on fire, according to the Montgomery County Sheriff's Office.

An autopsy found Purchase was sexually assaulted and strangled. Traces of a male’s DNA were found at the scene, according to the sheriff's office.

In May of 1986, the FBI ran the victim’s fingerprints, which positively identified her as Purchase, who had been missing from Houston, Texas.

In 2007, the Montgomery County Sheriff’s Cold Case Squad resubmitted the unknown male’s DNA.

Serial killer Henry Lee Lucas originally confessed to the crime in 1983, but both he and his alleged co-defendant Otis Elwood Toole were eliminated as suspects by DNA in 2008.

Lucas was a serial killer who murdered people between 1960 and 1983. He has three known vicitms, and several deaths that have not been verified. He confessed to more than 100 murders while in prison. He died of heart failure in 2001.

In October 2019, investigators sent the DNA in for genealogy testing.A lead generated from this genealogy search showed Thomas Elvin Darnell, 75, was a potential suspect. Detectives got a DNA search warrant for Darnell and compared it to the DNA from the scene.

On March 17 of this year, 38 years to the day Purchase was found, detectives collected a known DNA sample from Darnell.

On April 30, the DNA was positively matched the DNA from Darnell to that recovered from the scene, according to the sheriff's office. Darnell was arrested at his home on May 11.

Police have not revealed if there was a relationship between Darnell and Purchase or a possible motive for the killing.

On May 20, he was extradited to Montgomery County. He is currently being held in the Montgomery County Sheriff’s Office Jail on capital murder charges with no bond.