Lisa Ziegert was murdered in 1992, but her killer wasn't arrested until 2017

Investigators looking into the 1992 rape and murder of 24-year-old Lisa Ziegert knew they would need DNA evidence to solve the case. But the written confession from the killer fell into their laps unexpectedly.

Their big break came decades later, in 2017, when Gary Schara’s girlfriend provided investigators with the incriminating evidence.

“There were three separate letters,” Massachusetts State Police Trooper Noah Packer said in the interview with NBC’s Dateline, which will air Friday at 9 p.m. ET/8 CT. “One of them was essentially a confession letter. Another letter was a last will and testament. He also left a apology letter for the Ziegert family.”

In September of 2017, authorities sealed their case against Schara after searching his home and finding DNA samples matching the crime scene.

Says Pack, “We knew that we were gonna solve this case with a DNA match. We didn’t expect to solve this case by somebody writing confession letters.”

Lisa ZiegertCredit: Handout
Credit: Handout

Ziegert, a recent college graduate and teacher’s assistant, went missing from her second job at a gift shop in Agawam, Massachusetts, on April 15, 1992. Her car, keys and coat had been left at the store and authorities were notified when she didn’t show up to her job at Agawam Middle School the next day, MassLive reported.

Cold Case-Teacher Slain
Gary Schara
| Credit: Hamden District Attorney/AP

Four days later — Easter Sunday — Ziegert’s body was found off the side of Route 75 in a wooded area. She had been sexually assaulted, and an autopsy report later revealed that she had died of a single stab wound to the neck.

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Schara had been a person of interest in Ziegert’s death since 1993.

Last September, Schara pleaded guilty to first-degree murder. His arrest and conviction brought closure to one of the state’s most famous cases.

Dateline: The Music Box airs Friday, January 10 at 9 p.m./8 p.m. CT.