Just when you thought the Facebook ownership case couldn’t get more bizarre, there’s a new wrinkle to the civil suit filed by Paul Ceglia.

A letter reportedly sent by convicted killer James C. Kopp has been added to the court record in the two-year-old Facebook case, and it has federal court officials scratching their heads over how to handle it.

The letter, sent from the Canaan Federal Penitentiary in Pennsylvania, where Kopp is serving a life sentence for the 1998 assassination of Dr. Barnett A. Slepian at the obstetrician’s Amherst home, claims that Kopp and Ceglia have been pen pals for the past four years and outlines a series of claims and allegations about Ceglia, of Allegany County.

“Ceglia promised me $200 a month in prison commissary for the rest of my prison life if he won this lawsuit,” the letter from prison states. “Also Ceglia promised me a years subscription to Mens Health magazine and Yoga Journal if he won this fraud lawsuit, and told me he would fly down to prison in Pennsylvania to visit me every Sunday if he won.”

Officials at Canaan confirmed Kopp’s presence at the high-security prison near Scranton but said they could not confirm the authenticity of the letter.

Kopp, the anti-abortion activist known as “Atomic Dog,” was convicted in 2007 in Slepian’s assassination nearly nine years earlier. He was convicted of murder in Erie County Court and sentenced to 25 years to life.

The letter claims that Kopp has newly discovered evidence that Ceglia was involved in the Slepian murder but stops well short of revealing what it is.

It also claims that Ceglia told Kopp “he was going to lie and create a fraud lawsuit against Facebook” so he could use some of the money from a likely settlement to get Kopp a top-notch lawyer.

“In particular Bruce Cutler who defended John Gotti,” the letter states.

U.S. Magistrate Judge Leslie G. Foschio, who is handling Ceglia’s civil suit, added the letter to the public record this week, but it’s unclear how credible he and others view it.

Several court sources said the judge felt compelled to include the letter in the court record because of the nature of the allegations against Ceglia.

Lawyers for Ceglia could not be reached to comment Thursday. Ceglia is currently in federal custody in connection with a separate criminal case against him.

The letter, allegedly sent by Kopp acting on his own behalf, asks the court’s permission for Kopp to intervene in the civil suit.

Kopp, who has been in federal prison since 2007, admitted stalking Slepian in 1998, waiting in the woods behind the obstetrician’s Amherst home and then shooting him with a high-powered rifle as Slepian stood in his kitchen with his family.

During his jury trial, Kopp said that he did not mean to kill Slepian and that his only goal was to prevent him from performing abortions.

Ceglia’s civil suit against Facebook, in which he seeks at least 50 percent of the social networking giant, is based on his contention that he and Facebook co-founder Mark Zuckerberg signed a contract in 2003.

Facebook acknowledges that Zuckerberg signed a contract with Ceglia while Zuckerberg was a student at Harvard University but contends that it had nothing to do with Facebook.

Ceglia’s case against Facebook took a new turn two weeks ago when he was charged in Manhattan federal court with orchestrating a “multibillion-dollar scheme” to defraud the company,

Federal prosecutors claimed that Ceglia “doctored, fabricated and destroyed evidence” to support his ownership claims regarding Facebook, and they charged him with felony wire and mail fraud.

He posted bail earlier this week but has not yet been released.

If the author of the letter is indeed Kopp, he has gone a step further by now denouncing the anti-abortion movement.

“I support all abortions and I denounce the Lambs of Christ,” the letter writer said of the Pro-life group often associated with Kopp. “I’m a changed man and I seek a second chance in life.”