NASHVILLE, Tenn. -- A former Nashville attorney convicted of murdering his wife and plotting to kill her parents has filed a lawsuit against an inmate he says is the real killer.

Perry March filed the lawsuit against Barry Armistead in Davidson County Circuit Court on Tuesday. Armistead is serving time on an aggravated assault charge at Riverbend Maximum Security Institution, and March is serving a 56-year sentence at a West Tennessee prison.

March, 45, was convicted Aug. 17 after prosecutors used circumstantial evidence and testimony from jail inmates and his own father to convince the jury that he killed his wife, Janet Levine March in 1996. Her body has never been found, although his father, who is now deceased, told police he dumped his daughter-in-law's body in Kentucky.

In the lawsuit, March, who represents himself, accuses Armistead of having an affair with his wife, giving her drugs that allegedly caused her to overdose, and dumping her body.

Janet March "was in a relationship with defendant, and after she left her marital home on Aug. 15, 1996, she remained in the company of defendant until she passed away, sometime during the night," the lawsuit alleges.

March wants Armistead, 47, to pay him and any other interested parties compensatory and punitive damages and all other economic and emotional damages associated with the wrongful death of his wife.

The lawsuit is not the first time that Armistead's name has been associated with the March case.

On the first day of his murder trial, March's defense attorneys asked to interview the inmate because they believed he had written an anonymous letter confessing to the woman's murder.

Armistead was brought to court and denied writing the letter.