A man who pleaded guilty to killing a retired LaMoure County farmer seven years ago is having a tough time remembering where he dumped the body.

Authorities say they might use a polygraph or hypnosis to jog Steve Thomas' memory.

Thomas, 41, of Fargo, pleaded guilty to manslaughter on Friday and agreed to help authorities find the body of Norman Limesand, 82, of Marion, a neighbor who disappeared on Nov. 12, 1999. Authorities said the two had argued that day and Thomas shot Limesand.

LaMoure County Sheriff's Deputy Brad Devig said authorities have held a few searches since last week, but have found no trace of Limesand's body.

"(Thomas) said he was scared at the time, and it was dark, and he can't recall specifically where he put the body," Devig said. "He does remember that he drug the body in a cattail slough and left it there, on top of the ground."

Southeast District Judge James Bekken did not immediately set a sentencing date. The manslaughter charge carries a maximum penalty of 10 years in prison and a $10,000 fine.

Assistant Attorney General Jon Byers, who helped prosecute the case, said the plea agreement calls for Thomas to face a charge of murder if he is uncooperative in finding the body. He then could face life in prison.

But Byers and Devig said Thomas appears to be cooperating with authorities.

"As of right now, we have no reason to believe we have to withdraw from the agreement," Byers said. "From what I could tell, he appears to be trying to help."

Authorities said Thomas and Limesand argued over water drainage on the day Limesand disappeared. His pickup was found four days later, parked along a street in Moorhead, Minn. Authorities found blood on the pickup and tests showed it was Limesand's. He was declared dead in 2002.

The likelihood of finding Limesand's remains is slim, Byers said. "(The body) was exposed to elements and animals could have bothered it," he said.

Byers said a polygraph test and hypnosis can be used under the terms of the plea agreement.

"If anything comes from that and gives us a general location, we will do a mass search," Devig said. The searches would involve dogs trained to find human remains, he said.

Byers said authorities are hoping to narrow the search to a few sections of land in the county. "That's still a needle in a haystack, but it's a smaller haystack," he said.