BATON ROUGE - Attorneys made their opening statements Wednesday in the Baton Rouge murder trial of Ronald Dunnagan, who is accused of killing Gary Kergan in 1984.

Defense attorneys put pressure on the prosecution's star witness, Leila Mulla, saying there's no physical evidence linking Dunnagan to the crime. Dunnagan is accused of working with Mulla to poison Kergan, and she's expected to testify against him as part of a plea deal she made in exchange for a 30-year prison sentence.

Defense lawyer says no evidence implicates Ronald Dunnagan in this murder other than Leila Mulla's statement. @WBRZ

— Chris Nakamoto (@ChrisNakamoto) September 9, 2015

Investigators believe Kergan was beaten to death, but his body was never found. Authorities said they did find Kergan's blood inside the trunk of his car back in 1984. Prosecutors said Wednesday they believe Dunnagan chopped up Kergan's body to dispose of it.

Ted Kergan, the victim's brother, told News 2 he thinks jurors will find this a very simple case to decide.

"I think this is a very cut and dry case," he said. "It was a premeditated murder, there's things going to come out I don't want to talk about this second, later on they'll prove it was premeditated, they were both involved in it and I think the only defense for Dunnagan is to try to shift the blame away from him."

News 2 learned prosecutors offered Dunnagan a plea deal to avoid the trial earlier this week, but he turned it down.