BUFFALO, New York (CNN) -- James Kopp received the maximum sentence of 25 years to life Friday for the sniper slaying of a Buffalo, New York-area physician in his suburban home nearly five years ago.
Kopp, 48, faced at least 15 years behind bars after being convicted of second-degree murder in the 1998 death of Dr. Barnett Slepian, 52, a father of four.
Kopp has 30 days to appeal the sentence.
"It's clear the act is premeditated, there is no doubt about it," Erie County Court Judge Michael D'Amico told Kopp, according to a report by The Associated Press. "You made an attempt to avoid responsibility for the act. What may appear righteous to you is immoral to someone else."
The sentencing hearing was attended by members of abortion-rights organizations who had urged the judge to impose the maximum sentence.
"As a society we cannot allow people to take the law into their own hands in order to advance their own personal, political agendas," National Abortion Federation president Vicki Saporta said in a pre-sentencing letter.
In March Kopp was found guilty of intentionally killing Slepian, an obstetrician-gynecologist who also performed abortions. Slepian was struck by a single bullet fired from a high-powered rifle through a window of his suburban Amherst home.
Kopp claimed he meant only to wound Slepian. Prosecutors argued that Kopp's choice of a military assault rifle, and six unused bullets at the crime scene, proved that his claim was untrue.
Kopp still faces a federal trial for interfering with the right to an abortion. He is also a suspect in the nonfatal shootings of four other abortion providers in Canada and Rochester between 1994 and 1997.
Kopp did not testify at the one-day non-jury murder trial in March that he requested in lieu of a jury trial.
Kopp's decision to waive the right to a jury trial, opting to have the judge alone determine his guilt or innocence, was a surprise. At the same time, he decided not to contest the facts of the case. As a result, in an unusual one-day proceeding, Kopp agreed to a 35-page summary of the evidence presented by prosecutors.
The evidence included Kopp's Russian-made rifle, purchased from a Tennessee pawn shop in 1997 using a fake Virginia driver's license, his binoculars, and a baseball cap buried in the woods behind Slepian's house. DNA testing on hair fibers in the cap positively linked it to Kopp.
After the shooting, Kopp fled to Mexico, then Britain and France. The FBI placed Kopp on its 10 Most Wanted List in 1999.
He lived as a fugitive until French police, acting on a tip from the FBI, apprehended him at a post office two years ago. France extradited Kopp on the condition that the United States would not seek the death penalty.
He and Barket had originally hoped to use the trial as a forum for their anti-abortion views, and Barket had argued for an acquittal, reiterating Kopp's claim that he intended merely to wound the doctor.