A slander lawsuit against Congressman John Murtha is expected to be formally filed in U.S. District Court in Pittsburgh Thursday afternoon.

The litigation stems from a 2005 incident in Iraq and Murtha's reaction to it.

At that time, a group of Marines were accused of killing innocent Iraqi civilians in a raid in Haditha. Shortly after, Murtha appeared on various news broadcasts and characterized the Marines as cold-blooded killers.

The Marines were later cleared or wrongdoing in the incident.

One of the Marines, 24-year-old Cpl. Justin Sharratt, of western Pennsylvania, is suing Murtha for slander.

Murtha's comments about the incident have also served as the campaign focus for the man who wants to unseat Murtha in November, retired military officer William Russell.

Russell said, as a career military officer and 911 Pentagon survivor, he has a personal interest in seeing the record and reputations of the Marines cleared. He said a right to justice goes beyond politics. Even so, within the last couple of weeks, Russell's campaign launched a 60-second ad that focuses solely on Murtha's widely reported comments of the eight Marines at Haditha as "killing innocent civilians in cold blood."

Russell said on Thursday he has met with Sharratt and his parents, and said the federal lawsuit has been a long time coming. A legal fund was established when Sharratt was exonerated of the charges.

When asked if the timing of the lawsuit was politically motivated, Russell said, "Unfortunately this is a political fight that Mr. Murtha started. Mr. Murtha used his political office to forward his political agenda and if he wants to state that the Sharratt's are just playing politics, that's his fault. He started it."

Russell said Murtha should use the opportunity to admit his mistake and take responsibility for the harm the false accusations did to Sharratt and his family.

Murtha's press secretary said the congressman will not take questions with regard to the lawsuit, but said Murtha will respond to Russell's comments.

Stay with WJAC-TV News and WJACTV.com for continuing coverage.