More than 40 years after John Blaylock, Sr., 51, was found beaten to death at his Mansards apartment in Griffith in November 1981, a potential killer has been charged.

The case was unsealed Sunday against Gregory C. Thurson, now 64, of Eugene, Ore. He was arrested Oct. 29 and was held at the Lane County (Oregon) jail. He has been extradited to Lake County, according to court records and the Griffith Police Facebook page.

Police believe Blaylock died sometime between Nov. 1 and 3, 1981.

What is not immediately clear is how Thurson and Blaylock knew each other. The affidavit appears to suggest Blaylock was seen that night with Thurson, then 21, at a local bar, before they went to his apartment.

The case was built by forensic genetic genealogy — the same science where a lab traced DNA family trees to find the Golden State Killer, for example.

In Blaylock’s slaying, the blood was sent to the Indiana State Police for lab testing. There was no match in the national DNA database for offenders, but three brothers came back as a potential contributor on an October 2022 DNA hit from a blood drop on his bathroom sink.

Using that science, Parabon NanoLabs, based in Reston, Virginia, said it could preliminarily point to potential suspects as Theodore Thurson, Gregory Thurson, or a third brother named as “E.G., Jr.” in court documents.

From there, Gregory Thurson appeared to be identified by deductive reasoning, when the other two brothers were excluded as DNA contributors. It is unclear if Gregory’s DNA has been tested.

E.G. Jr.’s mother told investigators in October 2022 he was in a South Holland, Illinois, nursing home. He died in early December 2022. When a hair sample was sent to an Indiana State Police lab, the results excluded him.

By February 2023, the lab came back and said they narrowed the DNA hit to the biological son of a specific couple — i.e. either Theodore or Gregory Thurson.

Burnham, Illinois, police pulled Theodore over in May 2023. The cop collected a cigarette butt he tossed. When the lab ran his DNA, he was excluded, too, against the DNA from the blood drop.

However, when the Indiana State Police did a side-by-side comparison, it concluded it was highly likely — or 520,000 times more likely — whoever had the DNA from the blood drop was a direct sibling of Theodore Thurson. That left Gregory Thurson.

Court records do not yet list a lawyer.

Griffith Detective John Mowery, Jr. wrote he picked up the cold case in 2018.

Griffith police responded just before 3:30 p.m. on Tuesday Nov. 3, 1981, to the 1000 block of River Road, records show, Detective Stephen Markovich wrote then.

Blaylock’s two co-workers went over to his place when he hadn’t shown up for his shift at Inland Steel the prior day. His Sunday newspaper was still outside.

A Mansards apartments employee went inside. A bathroom light was left on.

He found Blaylock face down in a pool of blood on the bedroom floor. Blaylock had a pair of cut-off jean shorts over his head. He was in a white T-shirt and nude from the waist down.

Cops found clothes thrown around, including two new “velour sweaters” with tags attached from Zayre — a now-defunct retail chain on Cline Avenue and Ridge Road.

There were no signs of forced entry. The door had been locked. Griffith police Lt. William Wendell said Blaylock was asleep when he died, according to a Nov. 6, 1981 newspaper report. He believed he may have been beaten with a hurricane oil lamp and possibly knew the killer, since a key was found by his body. Blaylock’s wallet was “empty” and the apartment was “ransacked,” it said.

There was blood all over the apartment — on a living room cabinet, the back of the sofa, and on a blue jacket, inside china in a closet. There were blood spots on the bathroom floor as if it fell “straight down”, according to court records.

They also found blood drops on the bathroom sink and a stool.

In the bedroom, investigators found a blood-stained green towel. The headboard was splattered, with the mattress soaked with blood.

Cops found a shattered “piece of pottery” near Blaylock. His watch stopped at 2:15 a.m. Nov. 1. A clock “broken into several pieces” was near his feet.

It read 2:19.

Pathologist Dr. Alexander Custodio ruled his death a homicide from a skull fracture due to blunt force (trauma). He also had bruises, cuts and brain hemorrhages from the injuries.

His family, including two adult sons, and co-workers steered cops in 1981 to John’s Place, 1613 N. Cline Avenue. Blaylock was a regular, they said. The longtime bar is still in business today.

A female bartender told Weddell on Nov. 4, 1981 that she saw Blaylock, i.e. “Little Johnny”, at the bar from 1:30 a.m. to 2:30 p.m. with a “younger” man she didn’t recognize. He was 5’8’’ to 5’10’’, medium build, 20-23 with “straggly” “dirty blonde” hair and dark eyes, the affidavit states.

From there, the case went dormant until 2018 when Griffith police Chief Greg Mance ordered detectives to reexamine cold cases. The department’s social media post noted Mowery Jr. interviewed witnesses and surviving detectives, including his own father, retired Detective John Mowery Sr.

The Griffith Town Council voted to set aside money to help fund the lab fees, the post said.

In 1981, Blaylock was survived by three sons and four grandkids. His funeral was held in Tennessee where his mother lived.

mcolias@post-trib.com