WARREN (AP) — The triggerman in the Pamela Smart murder case — whose 1991 trial prompted sensational media coverage and spawned a Nicole Kidman movie — has been released from prison after serving nearly 25 years.

William Flynn was 16 and known as “Billy” in 1990 when he and three friends participated in what prosecutors said was Smart’s plot to kill her husband in Derry, New Hampshire. Flynn pleaded guilty to second-degree murder and served his sentence in Maine.

Also released on parole Thursday in New Hampshire is Patrick “Pete” Randall, who held a knife to Gregg Smart’s throat while Flynn shot him in the head.

Pamela Smart, who was 22 and worked as a media coordinator at the boys’ high school when her husband was killed, is serving life in prison without the chance of parole. She admitted to seducing Flynn but insisted she didn’t plan her husband’s murder.

The trial inspired the Joyce Maynard novel “To Die For,” which was made into the movie starring Kidman.

The board granted Flynn parole on his first attempt, on his 41st birthday in March.

He told the board that he’d always be haunted by the killing. “I will always feel terrible about what happened 25 years ago,” he said in March. “Parole will not change that.”

Flynn testified in Smart’s 1991 trial that she threatened to break up with him if he didn’t kill her husband.

On May 1, 1990, he and 17-year-old Randall entered the Smarts’ Derry condominium and forced Gregg Smart to his knees in the foyer. As Randall restrained him holding with a knife to his throat, Flynn fired a hollow-point bullet into his head.

Both Randall and Flynn were sentenced to 28 years to life in prison. Two other teenagers served prison sentences and have been released.