Olathe ? Prosecutors say college music professor David Lee Stagg strangled his lover and then tried to cover his crime by making it appear that the man committed suicide.

But in the first day of Stagg’s trial Tuesday, defense attorney Tom Bath countered that investigators can’t prove who killed William J. Jennings two years ago. He also said they have DNA evidence that actually clears his client.

Stagg, 58, a professor at the University of Central Missouri in Warrensburg, is charged with first-degree murder in the death of Jennings, 51.

Jennings, who co-owned Metropolitan Court Reporters in Overland Park, was found dead in his Shawnee home on April 25, 2004.

Assistant Dist. Atty. Scott Toth said Stagg killed Jennings after an argument and then went to work making it look like a suicide.

Toth said Stagg wrote a fake suicide note, moved Jennings’ car into his garage so it appeared he wanted to try poisoning himself with carbon monoxide and left two gas burners on the kitchen stove going. He also called Jennings’ home three times the day the body was found to make it look like his partner was still alive and later told an emergency dispatcher that Jennings had killed himself.

Stagg told the dispatcher that he had last seen Jennings about midnight when “we had a little disagreement. He told me to leave, and I left.”

Toth said Jennings’ home showed signs of a struggle with blood in several rooms.

Bath told a different story, saying that Stagg had worried about his partner for months, saying he was depressed and demanding that Stagg spend more time with him. He said the two got in fights over their relationship.

Bath said Stagg cooperated fully with investigators once Jennings’ body was found, allowing them to search his car and Kansas City condominium.

Bath said investigators had determined the blood found in Jennings’ home came from Jennings and a second person. He said that while there was too little of this second person’s blood to identify, there was enough to determine it wasn’t Stagg’s.

He also said police found fingerprints in the kitchen that didn’t match Jennings or Stagg.

“To this day, they (prosecutors) cannot tell you who that is,” Bath said.