PORTLAND — Convicted murderer Dennis Dechaine is scheduled for hearings in Portland Superior Court on Thursday and Friday for what could be his final bid for a new trial in the 1988 torture and murder of then 12-year-old Sarah Cherry.

Rockland-based lawyer Steven C. Peterson, who represents Dechaine, said Wednesday that months of DNA analysis will be the subject of the hearings, during which he’ll argue that the evidence implicates a man other than Dechaine — someone who was identified by Dechaine’s defense team years ago as an alternative suspect.

Though Deputy Attorney General William Stokes could not be immediately reached for comment Wednesday morning because he was in court, he has long maintained that more recent DNA analysis can’t erase the evidence against Dechaine and that the right man is in prison for the crime.

Peterson conceded that the prospect of winning a new trial for Dechaine is wrought with challenges.

“I have to be frank, the burden is on us to present clear and convincing evidence to show that a jury would have come to a different conclusion [had they seen the DNA evidence],” said Peterson. “We certainly feel that a jury may well have.”

In 2006, the Legislature enacted a law involving appeals of criminal cases that depend on new DNA evidence. It requires defendants to prove in court that the new DNA evidence only could have come from the perpetrator of the crime and that the DNA evidence must be strong enough to outweigh other evidence in the case.

DNA evidence was not presented in the original 1989 trial because the judge who has presided over the case through the years, Justice Carl O. Bradford, did not allow the defense to present alternative suspect arguments.

Dechaine and his supporters have tried to exonerate the former Bowdoinham farmer through numerous methods from arguments that time-of-death analysis in 1988 suggested Dechaine was in police custody when Cherry died to the contention that Dechaine was framed. But Peterson said advances in DNA analysis since 1989 have produced a more convincing argument for Dechaine’s innocence than he has ever had. Peterson said defense witnesses will testify beginning 9 a.m. Thursday, followed by the state’s witnesses on Friday.

Peterson said he has acquired a pure sample of an alternative suspect’s DNA — whom he can’t identify because of a court order — and that it is a partial match to some of the DNA collected from evidence found on Cherry’s body, which was discovered partially buried in a wooded area in Bowdoin.

“We have an alternative suspect’s DNA and that alternative suspect isn’t excluded [by the new DNA analysis],” said Peterson. “I suspect that the state will argue that because the DNA is partial mixtures and because we only have a sample, that it’s not very strong.”

The latest DNA testing focused on a shirt and bra worn by Cherry, as well as a scarf that was used to strangle her. DNA found in skin cells on the scarf was determined to not belong to Dechaine or Cherry and is consistent with basic characteristics of DNA from an alternative suspect. Peterson has said that the results are not 100 percent conclusive but could be enough to create reasonable doubt for a jury in a new trial.

DNA found on the shirt and bra was consistent with Dechaine’s DNA, though Peterson said that evidence is also not conclusive because the sample was too miniscule to provide a complete DNA profile. The testing was conducted by Orchid Cellmark of Texas and was funded by an organization called the Innocence Project, which works to exonerate people it believes are wrongly convicted.

Even if the new evidence is admitted into court and a new trial ensues, there is evidence that police officers and prosecutors have said for years strongly incriminates Dechaine. That evidence includes the fact that Dechaine and his truck were both found near the murder scene on the day Cherry was killed, that paperwork bearing Dechaine’s name was found in the driveway of the home where Cherry was baby-sitting, and pieces of rope used to bind Cherry were forensically matched to rope found in Dechaine’s truck and barn. Dechaine also is alleged to have confessed to the crime during police interrogation shortly after the murder, though his supporters dispute that.

Peterson said he expects that Bradford will order him and the state to file written briefs in the case, and a decision about a new trial could be weeks or months in the future. Dechaine, who is serving a life term in Maine State Prison in Warren, will be present for Thursday’s and Friday’s hearings in Portland.