Federal prosecutors sought two life sentences Tuesday for a militant abortion opponent already serving 25 years to life for murdering a doctor who performed abortions.

James Kopp's sentencing in U.S. District Court will bring to a close a case that began nearly nine years ago with the sniper-style slaying of Dr. Barnett Slepian in the kitchen of his suburban Amherst home.

Kopp was convicted in 2003 on a state charge of second-degree murder for Slepian's death and sentenced to prison. In January, a federal jury convicted him on related charges that he violated the Freedom of Access to Clinic Entrances Act by killing an abortion provider.

Assistant U.S. Attorney Kathleen Mehltretter said she would ask for consecutive life sentences on that count and a count of using a firearm -- in this case a scope-equipped military assault rifle.

"Dr. Slepian was gunned down in front of two of his children and his wife. A third child tried to help stem the flow of blood until paramedics arrived," Mehltretter wrote in her sentencing memo. "For the survivors, the horror of the gun shot and seeing a loved one killed will remain with them forever."

Slepian's four sons were ages 7 to 15 when their father was shot through a window of their home on Oct. 23, 1998.

Kopp, nicknamed "Atomic Dog," had been arrested more than 100 times protesting abortion. He is suspected in the non-fatal shootings of four other doctors, three in Canada and one in Rochester, and is charged with attempted murder in the 1995 shooting of Dr. Hugh Short in Ancaster, Ontario.

Canadian authorities have expressed interest in prosecuting Kopp, but he would have to finish his U.S. sentences first.

Judge Richard Arcara received letters from at least eight Kopp supporters seeking leniency for Kopp, 52, who claimed that he did not mean to kill Slepian, only to wound him to prevent him from performing abortions the following day.

Kopp, in a letter to the judge, wrote that several children are alive today because of Slepian's death. He used that claim to object to the $2.6 million in restitution prosecutors are seeking for Slepian's widow.

After shooting Slepian, Kopp fled to Mexico, Ireland and finally France, where he was captured in March 2001. He was added to the FBI's list of the Ten Most Wanted fugitives in June 1999.