A 76-year-old man has been convicted in the 1992 strangulation death of an Illinois teenager.

Robert Serritella, of Park Ridge, was found guilty Thursday on two counts of first degree murder in the killing of 15-year-old David Chereck, of Skokie.

The teen was found strangled with a scarf in a forest preserve Jan. 2, 1992. He had last been seen a day earlier, walking home from a bowling alley in Skokie.

Serritella, a convicted sex offender, later incriminated himself in conversations with people in California and Utah, authorities said. He was arrested in California in 2014 and charged in the killing.

"The state proved the defendant guilty of both counts of murder," said Cook County Circuit Court Judge Lauren Edidin, after the four-day bench trial in the Skokie courthouse.

Chereck's "life was tragically ended by the defendant in a violent and cruel way," Edidin said.

The decision drew tears from Chereck's mother, Esther, who testified Monday during the first day of the trial.

"I'm so relieved. I'm so relieved," she whispered in the courtroom.

After the trial, she embraced friends and family and said: "He got justice."

The state's attorney's office and the Cook County sheriff's office collaborated in the investigation.

"He talked and he talked and he talked," said Assistant State's Attorney Ethan Holland. "To police, to reporters, to his friends, to Esther, to cellmates."

Serritella's statements repeatedly put him in a white car at the time and place of Chereck's disappearance and death, Holland said. Three of Cherek's friends testified that they remembered noticing a white car idling near the park where they were socializing that night.

"If it wasn't for (Serritella's) refusal to remain silent," said Holland, the cold case may have never gone to trial.

The trial included the testimony of a man who said Serritella solicited him for sex when he was 16 years old in 1991. In phone conversations, Serritella would frequently discuss explicit sex acts, including strangulation, the man testified. In their talks, Serritella proposed they meet in a forest preserve, he said.

Serritella had rejected a plea deal that would have released him from prison in five years. In exchange for the agreement, Serritella needed to plead guilty to murder in Chereck's death. Serritella maintained his innocence. He could now be sentenced to 20 to 60 years in prison.

Sentencing is scheduled for June 19.

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Information from: Chicago Tribune, http://www.chicagotribune.com