PORTLAND – The lawyer who’s reviewing the attorney general’s file on the murder case against Dennis Dechaine plans to proceed with an appeal based on DNA evidence that was not considered at his trial.

New tests of blood under the fingernails of victim Sarah Cherry show the presence of DNA from someone other than Cherry and Dechaine.

Police, prosecutors and Cherry’s family say there is no proof the mystery DNA is connected with her slaying. But Dechaine’s former lawyer, Tom Connolly, said the existence of a third person could have opened the door to the theory that someone other than Dechaine killed Cherry.

Dechaine is serving a sentence of life in prison for the slaying of Cherry, a 12-year-old Bowdoin girl. Her body was found July 8, 1988; she had been strangled, stabbed and raped with sticks.

He has maintained his innocence despite damning evidence: Police found papers bearing his name outside the house where Cherry was last seen alive; his truck had been parked across a dirt road from the grave site; and her body was bound with rope cut from a piece of rope in his truck.

Dechaine also lied to police, saying first that he had been lost in the woods and then saying he went to the woods to get high. After his arrest, he made a series of incriminating statements to police.

Dechaine’s latest defense lawyer, Michaela Murphy of Waterville, is preparing a motion for a new trial with the assistance of the Innocence Project, a national group founded by Barry Scheck, a member of the O.J. Simpson “Dream Team.” The Innocence Project has used DNA evidence to free 125 wrongly convicted people around the country.

The clippings from two thumbnails likely will be the crux of his case. A 2-year-old state law allows people serving sentences of more than 20 years to use DNA evidence as the basis for requesting new trials.

The clippings were kept in an envelope after the state crime lab analyzed eight of Sarah Cherry’s fingernails to determine the blood type of the stains. It turned out to be the same blood type as Cherry’s.

From the beginning, Connolly said, he wanted to introduce evidence of another suspect at trial. But Justice Carl Bradford refused to allow it, saying there was no evidence to support Connolly’s theory.

Bradford also denied a motion for DNA testing of the thumbnails. At that point, DNA tests had never been used as evidence in a U.S. criminal trial.

After Dechaine’s conviction, Connolly fought again to get the thumbnails tested, and again Bradford refused. But two years later, the fingernails wound up in the lawyer’s possession.

Connolly received a routine form letter from a court clerk, telling him the exhibits from the Dechaine case would be destroyed if he didn’t pick them up. He wrote back to say that Bradford had issued an order blocking him from doing anything with the evidence.

Connolly picked up the fingernails when he received a second form letter, signed by Bradford, demanding he pick up his exhibits. As Connolly later told a furious Bradford, “I stole them fair and square.”

Connolly consulted with Barry Scheck, who arranged for the nails to be tested for $1,500.

Friends and former classmates of Dechaine’s in Aroostook County raised the money through a dance in 1993. Later that year, they got the tests that Dechaine had always wanted.

William Stokes, Maine’s deputy attorney general, said the DNA evidence doesn’t make all of the other evidence go away. And he said there was more evidence in Dechaine’s trial than in a typical murder trial.