BRENTWOOD, N.H. (AP) -- A tearful and shamed William Flynn apologized Friday to the family of the man he murdered 18 years ago, saying he pulled the trigger as a vulnerable teen at the behest of the only person who made him feel loved and important: Pamela Smart.

"I know that I can never make amends for the pain ... and I promise you I will carry this guilt and remorse with me every day for the rest of my life," Flynn said at Rockingham County Superior Court. "It has never diminished and I hope it never will."

Flynn, 33, spoke at a hearing on his request to reduce his 28 years-to-life sentence in the murder of Gregory Smart in 1990. He isn't eligible for parole for another 10 years but is asking to be released now that he has spent more than half his life behind bars.

The state and Gregory Smart's family objected. Smart's brother, Dean, angrily ridiculed Flynn's written request for early release, noting that Flynn mentioned himself 85 times but made only four references to the man he killed.

He also took issue with Flynn's assertion that his desire to help others springs from his quest for forgiveness. Flynn has been active in charities and youth outreach programs while incarcerated at the Maine State Prison.

"You think your respect for life and desire to help others comes from Gregg, the man you murdered?" Dean Smart said incredulously. "It's your desire to get of jail early that drives you to do your charity work. You do your charity for your own pathetic cause. If you truly wanted forgiveness, you would serve your complete sentence as a man of your word."

But Smart's father, William, took a softer approach, admitting later that Flynn's tears got to him. He detoured from his prepared speech to tell Flynn that he would agree to let Flynn out of prison when he's 40, but for now adamantly opposes his release.

"I will fight you with my last breath and last heartbeat and I am not a well man," he said.

Flynn said that as he entered the courtroom, he felt "a tremendous shame," then tried to explain to Smart's family how he could kill their loved one.

"(Pamela Smart) was an adult I thought cared about me, paid attention to me," Flynn said, constantly wiping away tears. "I had never felt important before. Not only was she an adult, she was attractive. All the guys in school were attracted to her."

Flynn said he felt abandoned by his mother, lost the only disciplinary figure in my life when his father died and acted out, with no consequences, for years.

"It felt like nobody cared enough even to discipline me," he said. "I just had a general feeling of being worthless and isolated" until he met Pamela Smart in a self-esteem class she helped teach at his high school.

"She came into my life at time I was most vulnerable and filled all those voids in my life," he said.

They began a sexual relationship and Smart quickly "made herself most important thing in my life," he said, threatening to end their relationship — and his world — whenever she felt he wasn't being sincere.

Eventually, he has said, Smart convinced him that the only way to continue the relationship was with her husband out of the way.

On May 1, 1990, Flynn and a friend entered the Smarts' condominium and grabbed Gregory Smart. According to Flynn's trial testimony, the friend held a knife to Smart's throat, and Flynn — after asking God for forgiveness — fired a .38-caliber revolver. Two other teenage friends were in a getaway car.

"I desperately want you to know I'm not that weak person anymore," he said Friday.

"I know none of this excuses what I did," he said. "I take full responsibility for my actions. Every day I think about what I've done to you and the people I hurt and I'm terribly and deeply ashamed of myself for being so weak."

Gregory Smart's father thanked Flynn for his apology.

"I accept it and may God bless you," Smart said, but added that it is too early for him to be released.

"You had every opportunity given to you that night to get the hell out of there," he said. "At 16 you should've known the difference between right and wrong."

Since entering prison, Flynn has earned a GED, taken college computer courses and earned an electrician's helper license. He has gotten married to a woman six years his senior. His court file contains more than a dozen letters of support from prison employees, friends and people who say they would hire him if he is released.

"This is a man worthy of the court's mercy," said Flynn's lawyer, Cathy Green. "He grew up in prison. He has the strength of character and strong moral fiber to be a contributing member of society."

She argued that the three goals of imprisonment — punishment, deterrence and rehabilitation — all have been met.

"We need to be very clear," she said. "He will continue to be punished for the rest of his life."

The state objected to Flynn's request, saying he was rewarded for his cooperation and youth with the current sentence. Senior Assistant Attorney General Susan Morrell said Flynn's efforts to better himself should not overshadow the brutal nature of his crime.

"The message to the community listening today, as they listened 17 years ago, must be clear: No matter your age or circumstances, when you commit premeditated, cold blooded murder, you will spent the majority of your life in prison," she said.

Flynn pleaded guilty to second-degree murder, cooperated with prosecutors and was a key witness against Smart in her sensational trial. Smart, who is serving a life sentence, does not deny the affair but maintains she had nothing to do with the murder.

Judge Kenneth McHugh did not indicate when he would rule on Flynn's request.

"There are never any winners in cases like this," he said. "Everyone loses."