Leonard Peltier is serving two life sentences for the murder of two FBI agents on the Pine Ridge Indian Reservation in South Dakota in 1975. But decades after his conviction, the case — and his supporters' renewed bid for clemency — still prompts emotional debate.

He should die in prison, say many former FBI agents, including some who once headed the agency's Minneapolis regional headquarters.

He is innocent and should be released, argue Peltier's supporters, Twin Cities activists among them.

Amnesty International has taken up Peltier's case, forwarding about 100,000 e-mails to President Obama asking for clemency. The group is backed by an array of advocates including Minneapolis folk singer Larry Long, who made a video about Peltier's case that has been viewed more than 80,000 times online.

In the video, Twin Cities attorney Larry Leventhal, who has represented the American Indian Movement (AIM) for years, says Peltier has languished in prison for "a crime that the evidence shows he could not have committed."

But many FBI agents are adamant that Peltier, 72, is guilty and should remain in prison.

"I have called him a mad dog and that is exactly who he is," said Nick O'Hara, former special agent in charge of the Minneapolis bureau. "He never should be released to prey on either citizens of the Native American community or the community at large."

Larry Langberg, president of the Society of Former Special Agents, appealed to FBI retirees in the August issue of the group's magazine, the Grapevine. He asked them to write letters to Obama and U.S. Attorney General Loretta Lynch, urging "No Parole for Peltier."

Deborah Pierce, another former special agent in charge of the Minneapolis FBI office, said, "He murdered two FBI agents in cold blood and should never be let out of prison."

In poor health

Peltier, an AIM activist, was convicted in 1977 of killing two FBI agents, Ronald A. Williams and Jack R. Coler. They were investigating another case on the reservation when the shootout began. Two other AIM members accused in the murders were acquitted.

Peltier's supporters raised questions about the fairness of the trial. They asked President Bill Clinton to pardon Peltier as he left office, but that request was unsuccessful.

The FBI mobilized against Peltier's release then, too.

"That's why he's still there," Leventhal said in an interview this week.

Justin Mazzola, a spokesman for Amnesty International in New York, said that Peltier, imprisoned in the U.S. Penitentiary in Coleman, Fla., is in poor health.

He said appeals through the courts have been exhausted and Peltier deserves clemency because of his "inability to call certain defense witnesses that would have challenged the testimony that was presented by the government, as well as evidence that was kept from the defense at trial which only came out afterward."

Long believes Peltier is not guilty. His new album includes the song "Lay Hatred Down," which is dedicated to Peltier.

"It's time that Leonard come home," he said.

Outgoing presidents often make pardons in their final days in office. Obama's final day in office is Jan. 20.

Twitter: @RandyFurst