SPRINGFIELD — Gary E. Schara pleaded guilty Wednesday in Hampden Superior Court to first-degree murder in the 1992 slaying of Lisa Ziegert, bringing an abrupt and unexpected end to the case just over two years after his arrest.

“I am here to make a change of plea your honor,” Schara, appearing gaunt and dressed in a red jumpsuit, told Judge Michael Callan shortly after he entered the courtroom.

Hampden District Attorney Anthony Gulluni — whose office relied on advances in DNA technology to narrow the field of suspects and ultimately link Schara to the killing — told the judge Schara was pleading to first-degree murder under the theory of extreme atrocity and cruelty. Gulluni said his office is dropping charges of kidnapping and aggravated rape, which had expired under the statute of limitations.

Schara’s plea, which came with no trial date set, is a rare case of a defendant admitting to first-degree murder in Massachusetts, where the charge carries a mandatory sentence of life in prison without possibility of parole. Asked by the judge whether he agreed to give up “forever” his right to a jury trial, Schara said, “Yes, I do.”

Gulluni said he would submit a letter to the Department of Corrections recommending that Schara serve his sentence at MCI-Norfolk. Defense attorney Paul Rudof asked the judge to recommend Norfolk.

Schara listened intently as the district attorney read a lengthy statement outlining the facts of the case, a final step before Callan could accept the plea.

At the end of Gulluni’s statement, the judge asked: “Are you the person described in those facts who murdered Lisa Zeigert?”

“Yes sir,” Schara replied.

Ziegert, 24, was a teacher's assistant in Agawam Middle School when she was abducted from her second job at Brittany's Card & Gift Shoppe on Walnut Street Extension in Agawam on April 15, 1992. Her body was found four days later in a wooded area off Route 75.

Her death remained one of the region’s most notorious cold cases for over two decades, with no suspects publicly identified until Schara’s arrest.

Officials have said the endgame began when a state trooper went to Schara’s West Springfield apartment in September 2017 with a court order for him to provide a DNA sample. But Schara wasn’t home, and he left the area after learning about the trooper’s visit. He was arrested on Sept. 16 at Johnson Memorial Medical Center in Stafford Springs, Connecticut, where he sought treatment after he tried to kill himself.

At arraignments in Westfield District Court and Hampden Superior Court he pleaded not guilty to charges of murder, kidnapping and aggravated rape.

Over the course of the investigation, "hundreds" of potential suspects were considered and ruled out, Gulluni said at the time of the arrest.

Schara, now 50, was identified as a person of interest as early as 1993. His estranged wife, Joyce McDonald Schara — who died in 2014 — contacted police in 1993 and said she believed her husband could have some connection to the case, a relative previously told The Republican / MassLive.

But it wasn’t until 2017 that DNA analysis delivered the evidence prosecutors needed to bring charges, officials have said.

That break in the case came a year after another key milestone. In September 2016, Gulluni’s office released a composite image of a possible suspect, the product of a new technology known as DNA phenotyping. The process relies on DNA — in the Ziegert case, evidence collected in 1992 — to predict attributes such as genetic ancestry, face shape, and hair and eye color.

"For the first time in twenty-four years, we have a face to this crime," Gulluni said at the time.

Officials have said the image, which matched many of Schara’s features, was not the sole reason investigators put him on their short list of suspects, but they described it as a contributing factor.

At the time of Ziegert’s death, meanwhile, the use of DNA in criminal prosecutions was in its infancy. The first conviction based on DNA evidence was in New York in 1988, and the state’s supreme court didn’t uphold the verdict until 1994. Massachusetts courts did not allow DNA evidence as admissible until 1997.

The evidence gathered in the Ziegert case eventually yielded a DNA profile for a single male source — essentially giving investigators the killer's identity without offering his name or location. When Gulluni released the composite image in 2016, he said the DNA profile had yielded no matches in any law enforcement databases.

Ziegert’s family held hope for years that DNA science would help solve the case. In 1995, her parents — George and Dianne “Dee” Ziegert — made an $1,100 donation o the Agawam High School science department to purchase equipment for genetics classes to study the relatively new science.

After Schara’s arrest, George Ziegert described the family’s reaction as feeling like they’d won the lottery.

"We got the big answer," he said in September 2017, adding: "I don't think people can imagine how many people were involved through the law enforcement over the years, and they just kept on with it and kept on with it. It just boggled our mind with the fact that that would happen."

This is a developing story. Updates will appear on MassLive throughout the day.