George Clarence Seitz, an 81-year-old WW I veteran, left his Jamaica, Queens home on Dec 10, 1976 to get a haircut. He was never seen or heard from again.

In a Queens courtroom Tuesday, Martin Motta, 75, a former barber in the borough who had been friends with Seitz for years, admitted killing the Army vet, dismembering his body and burying the remains in the backyard of a house in Richmond Hill.

Police said the motive was robbery since Seitz usually carried large sums of cash. His remains were recovered in 2019 based on a tip, the NYPD said. It remained unclear whether Seitz was planning to visit Motta the day he disappeared.       

Motta’s conviction on manslaughter charges for the killing of Seitz is the first in New York City obtained through genetic genealogy, a forensic technique that is proving to be a major development in solving cold cases around the country, including Long Island.

“No matter how much time has passed, we will use every tool at our disposal to achieve justice,” said Queens District Attorney Melinda Katz in a statement.

The technique, in which unknown genetic profiles are compared to samples from individuals who have submitted their DNA to public genealogical sites such as 23andme, has been used successfully in two major Long Island cases.

Investigators matched the DNA of the remains found in 2019 to Seitz, a witness to the crime came forward, and Motta was eventually arrested.

Earlier this year, Suffolk County Police…