BOSTON – One of the men convicted of killing 10-year-old Jeffrey Curley asked the state’s highest court on Friday for a new trial, arguing that DNA evidence showing his semen in his co-defendant’s car biased the jury against him.

Salvatore Sicari was convicted of first-degree murder in the kidnapping and murder of Curley in October 1997.

Sicari and his co-defendant, Charles Jaynes, lured Curley into a car by promising him a bicycle, then killed him by holding a gas-soaked rag to his mouth after he resisted their sexual advances. They threw his body into a river in South Berwick, Maine.

Jaynes was convicted of second-degree murder and both men were sentenced to life in prison.

In arguments before the Supreme Judicial Court Friday, Sicari’s lawyer, Dana Curhan, said the jury should not have been allowed to hear about DNA samples that showed Sicari’s semen in Jaynes’ car.

The semen evidence was originally ruled inadmissible by a Middlesex Superior Court judge after prosecutors mentioned it in their opening arguments.

But a single justice of the SJC later overturned that decision, ruling that excluding promised evidence would bias the jury against the state.

“There was absolutely no evidence linking [Sicari’s semen] to the crime,” Curhan said after Friday’s arguments before the SJC.

“Mr. Sicari had been in the car hundreds of times before the incident and there was ample opportunity for him to have left the stains during another time.”

Prosecutors, however, argued that the evidence was properly admitted to help place Sicari at the crime scene.

The defense also argued that Sicari’s confession should have been suppressed because Cambridge police improperly continued to question Sicari after he stopped answering questions and remained silent for about 30 to 40 minutes.

Curhan said police should have taken his silence as an invocation of his right to remain silent or sought to clarify whether he was invoking his right.

Later in the interview, Sicari made incriminating statements.

Prosecutors argued that Sicari initially waived his right to remain silent and repeatedly spoke with police. They argued that defendants must clearly articulate their intention to invoke the right to remain silent.