BOSTON— Benjamin LaGuer, convicted of the brutal rape and beating of his 59-year-old former neighbor at a Leominster apartment complex in 1983, made his latest bid for a new trial to the state Appeals Court yesterday.

Mr. LaGuer, 42, was sentenced to 15 years to life in prison in 1984. He has maintained his innocence since his arrest and has amassed a high-profile group of supporters, including former Boston University President John Silber. Mr. Silber attended yesterday’s hearing at the John Adams Courthouse in Boston.

The victim’s son-in-law was also present, and said after the hearing that his family remains dedicated to keeping Mr. LaGuer behind bars.

The Appeals Court’s decision is not expected for weeks or months, lawyers said after oral arguments yesterday.

Mr. LaGuer waged a lengthy battle to have evidence subjected to DNA analysis, a technology that was not available at his trial in 1984. The results of the analysis in 2002 further implicated Mr. LaGuer, but he has since sought to discredit the findings. He has found several experts who said the results could have been compromised by contamination.

The DNA testing was barely discussed yesterday, however. The issue at the heart of the latest appeal — Mr. LaGuer’s eighth bid for a new trial — is a fingerprint report that was not shared with Mr. LaGuer’s defense until late 2001.

Defense lawyer James C. Rehnquist, son of the late U.S. Supreme Court Chief Justice William H. Rehnquist, argued before a three-judge panel yesterday that Superior Court Judge Timothy S. Hillman erred when he denied his client’s motion for a new trial.

Mr. Rehnquist argued that the fingerprint report could have played a significant role in the jury’s deliberations in 1984.

The victim, who died in 1999, was bound by a telephone cord in her apartment during an assault that prosecutors said lasted eight hours. She identified Mr. LaGuer in court as her attacker.

Leominster police Officer Ronald N. Carignan, now deceased, testified at Mr. LaGuer’s trial that a partial fingerprint was taken off the base of a telephone and it did not match Mr. LeGuer.

In 2001, during a lengthy series of court hearings surrounding Mr. LaGuer’s bid for DNA analysis, state police recovered the first page of a fingerprint report generated days after the crime in July 1983. That report said four fingerprints were collected off the telephone, none of which matched Mr. LaGuer.

The report said those results were shared with Officer Carignan, the lead detective on the case.

Assistant District Attorney Sandra L. Hautanen, who did not prosecute the original case against Mr. LaGuer, told the Appeals Court she did not know why that fingerprint report was not shared with the defense more than 20 years ago. But she argued the findings would not have made a difference, since the jury relied on the victim’s identification to convict Mr. LaGuer.

She said the court transcript showed Mr. LaGuer’s lawyer at trial grilling Officer Carignan about fingerprint evidence. Officer Carignan, who had been instructed to testify only about his own observations, said he recovered only one partial fingerprint.

Mr. Rehnquist argued earlier that the report had more weight than that granted by Judge Hillman. He said jurors were not swayed by an inconclusive partial print, but four fingerprints that matched someone other than Mr. LaGuer would likely have had more impact.

“That’s a critical distinction, your honor,” Mr. Rehnquist told Justice Mel L. Greenberg. “This case was all about identification. There was absolutely no physical evidence that linked Mr. LaGuer to the crime.”

Mr. Rehnquist also said the victim’s identification of Mr. LaGuer was not “clear and consistent.”

During her argument, Ms. Hautanen said the lack of physical evidence was partly attributable to Mr. LaGuer, who years later admitted to contaminating the saliva sample he was ordered to provide the court before his trial.

Justice Greenberg asked Ms. Hautanen about the potential value of the fingerprint report to the defense. He said the defense had identified, by name, another man who could have committed the crime, and said the fingerprints collected off the telephone could have been compared with that man’s prints.

“That’s pretty significant stuff,” Justice Greenberg said. “He was never given that opportunity.”

Ms. Hautanen said Mr. LaGuer told the victim that he would kill her if she told anyone who he was, so her initial remarks to police that she did not know who attacked her were influenced by fear.

Later, she said, the woman told her daughter it was her neighbor, later identified as Mr. LaGuer, who had raped and beaten her. Ms. Hautanen said the room was bright enough for the woman to see her assailant.

“She had been with him for eight hours, your honor, face to face,” she told Justice R. Malcolm Graham.

Mr. LaGuer has twice been denied parole and will be eligible for parole again in 2008. Among other issues, parole board members cited his refusal to accept responsibility for the crime. Mr. LaGuer has said he wants to clear his name and will not confess to a crime he did not commit.

Outside the courtroom, Mr. Rehnquist said the DNA issue would be addressed at a new trial. The question before the court right now, he said, is whether the evidence withheld from the defense at Mr. LaGuer’s trial in 1984 was itself grounds for a new trial.

Mr. Silber was joined in the courtroom by Boston University professor Leslie Epstein, Minister Don Muhammad of the Nation of Islam and members of Mr. LaGuer’s family.

Mr. Silber, who donated thousands of dollars toward the DNA analysis, has stood by Mr. LaGuer and testified on his behalf before the state Parole Board in 2003. He said there had been so many irregularities connected to the case that it warranted another look.

“I don’t think there is any question a new trial is needed,” Mr. Silber said yesterday.

Robert Barry, the victim’s son-in-law, said his family would remain vigilant in the case as long as Mr. LaGuer fights his conviction.

“He has to own up to his crime and we’re still going to pursue it,” he said.

Mr. LaGuer, who has cited ineffective assistance of counsel and allegations of racism on the jury in previous efforts to win a new trial, is an inmate at the Souza-Baranowski Correctional Center on the Lancaster-Shirley line. He was not present for the oral arguments yesterday.

He said in an interview this week he was grateful to have his case argued before the Appeals Court.

“I hope that a new trial is granted and a new trial is held,” Mr. LaGuer said. “Because the DNA evidence certainly did not tell the truth.”