PORTLAND — A lawyer for convicted killer Richard Dwyer asked the state’s high court Wednesday to give his client a new trial.

George Hess appeared before the Maine Supreme Judicial Court to appeal Dwyer’s murder conviction and life sentence.

A jury found a year ago after a four-day trial that Dwyer, 46, of Canton, robbed, raped and murdered 38-year-old Donna Paradis, who was seven-and-a-half months pregnant. Her naked body was found in a shallow grave in November 2007 behind the Promenade Mall in Lewiston, strips of cloth looped around her wrists and neck. Prosecutors said she had been strangled.

Police said Dwyer had lured her into his confidence a month earlier with the promise of a used car. The two worked together at a Lewiston company near where her body was discovered. She had withdrawn $400 in hundred-dollar bills from her bank shortly before she disappeared. Dwyer was captured on tape buying a pickax and shovel to bury Paradis’ body, apparently with her cash.

Hess filed a 40-page brief with the law court, arguing that the trial court made 10 mistakes before Dwyer’s trial, during the trial and at sentencing.

Of those points, Hess raised three during oral arguments before the seven-member panel of judges on Wednesday.

He told the justices that he should have been allowed to present evidence that DNA matches are less reliable than most people believe because two unrelated people can have similar DNA.

“In the mind of the public, DNA evidence is irrefutable,” Hess said. “However, we believe that recent events raise questions concerning this perfect identification evidence.” He cited studies in other states that found sometimes the same genetic markers can be found in unrelated people.

Also, he questioned whether the jury should have been allowed to learn about crime-scene evidence that contained mixed DNA from more than one person, which resulted in a weaker probability of a match.

Assistant Attorney General Donald Macomber told the judges the kind of DNA database search Hess was seeking would have produced unreliable results. The lower court made the correct ruling, he said.

During questioning from justices, Hess was asked whether he had the opportunity to cross-examine the state’s expert witness about the statistical probabilities stemming from the DNA evidence. He said he had.

“Wasn’t that sufficient?” Associate Justice Ellen Gorman asked.

“That’s only one tool in a defense arsenal,” Hess said.

He told the panel the trial judge should have allowed the case to be moved to a different community because readers’ comments on local online media reports during Paradis’ disappearance reflected a bias against Dwyer.

Macomber said Hess never claimed that the jury picked for the trial was, in fact, biased by the news coverage of the case.

“As we address this new electronic age where people can communicate so quickly, and without actually knowing each other, why isn’t a blog really just an analogy to the local coffee shops?” Chief Justice Leigh Saufley asked.

“People will talk about what they’re thinking about,” she said. “They’ll respond to newspapers. They’ll respond to the television. And the judge’s job remains exactly the same: that is, to make sure the people who are on the jury are not people who have made up their minds.”

Hess also said the trial judge should have considered Dwyer’s unfortunate upbringing, including being raised in a broken home and abandoned by his alcoholic father at a young age, in deciding the defendant’s sentence.

Macomber said the judge did that but concluded Dwyer’s history shouldn’t be a mitigating factor that would reduce the number of years Dwyer should serve in prison.

The court is expected to review the written and oral arguments and rule later on the case.