RIVERHEAD — A young man who confessed to murdering his sleeping stepfather with a samurai sword but later blamed his mother for the killing amid claims he was sexually abused by the victim was sentenced yesterday to 25 years to life in prison.

Zachary Gibian, 20, of Hauppauge, was convicted last month of second-degree murder after testifying that Scott Nager, 51, a retired New York City police officer, had sexually abused him since age 15. Gibian made no statement at his sentencing, but his attorney said he intends to appeal.

Prosecutors said the allegations of sex abuse were “preposterous.”

After the proceeding, Nager’s relatives and friends expressed hope that the victim would someday have his sullied reputation restored. At least a dozen of Nager’s former New York Police Department colleagues sat in the front rows of the Suffolk County courtroom.

“I think he got what he deserved,” the victim’s 82-year-old father, Nathan Nager, said, referring to the young man he had once called his grandson. “If he showed remorse, I wouldn’t feel that way. Can you imagine accusing child abuse? It’s unbelievable.”

Wearing a replica of her brother’s NYPD shield No. 15901 on a necklace, Ann Leonardi addressed state Supreme Court Justice Robert Doyle on behalf of her family.

She called the victim “the kindest husband and father a wife or son could want” and said she was disgusted by the allegations of sex abuse.

“It was all about money and greed,” she said, not abuse.

Gibian, who gave written and videotaped confessions to police just hours after the February 2005 killing, changed his story on the witness stand. He insisted that it was his mother who inflicted the fatal blows after she discovered her husband sexually abusing him. Prosecutors said there was no evidence of any sexual abuse in the Hauppauge home.

Nager, who had an extensive war memorabilia collection, was nearly beheaded as he slept on his living room couch.

His wife, Laura Nager, has maintained her innocence throughout. After the sentencing, her lawyer, Steven Wilutis, said he was told by prosecutors to expect an arrest, although he was not told on what charge. Suffolk County Assistant District Attorney John Scott Prudenti said the investigation into Laura Nager remains active, but he declined further comment.

Prosecutors have contended that Scott Nager was a concerned parent trying to rein in a rebellious teenager.

“He’d seen a lot of people on the streets go bad and he didn’t want that for his own son,” Mr. Leonardi said.

“Scott was a great guy; he was an excellent police officer,” a retired police officer who was Nager’s partner in the 34th Precinct in the Washington Heights section of Manhattan, Daniel McGuire, said. “He cared about people. He saved people’s lives.”

Gibian claimed that numerous times, beginning when he was about 15, Nager would get drunk and repeatedly force him to perform a sex act on him — sometimes with a pistol against the boy’s head. He testified that Laura Nager learned of the abuse the night before the killing, when she walked in on her husband and son in the teen’s bedroom.

But Mr. Prudenti said, “The defense put the victim on trial in the court of public opinion.”

The prosecutor noted that when Laura Nager was interviewed by the county probation department in preparation for a pre-sentencing report on her son earlier this month, she disavowed her son’s abuse allegations.

“She claims she never witnessed any sex abuse whatsoever, which is in direct contradiction to the defendant’s outlandish claims,” Mr. Prudenti said.

A key prosecution witness at the month-long trial was Gibian’s friend Troy “T.J.” Harrelson, the son of former New York Mets star and manager Bud Harrelson. The younger Harrelson, who recalled few specific details because of his admitted use of marijuana, cocaine and OxyContin, said that he went to Gibian’s home after his friend called him for a ride on the morning of the killing.

He said when Gibian got in his car, he admitted he had just killed his stepfather and then asked Mr. Harrelson to help him dispose of the murder weapon and other items in a trash bin behind a shopping mall.

Mr. Harrelson cut a deal with prosecutors and pleaded guilty to hindering prosecution. He faces 90 days in jail and five years probation, pending the outcome of court-ordered drug treatment.

Gary Gibian, Zachary’s natural father, who now lives near Chicago, stood by his son after the sentencing.

“My son is innocent,” he said. “We’re going to appeal this case.”