Couer D’Alene, Idaho ? Detectives who questioned a man in the killings of three people ruled him out as a suspect Thursday and said they still had no idea where two children missing from the family’s home were.

The man, Robert Roy Lutner, 33, of Hayden, voluntarily took and passed a polygraph test during a seven-hour interview with investigators, Kootenai County sheriff’s Capt. Ben Wolfinger said. Lutner said he saw the three alive when he attended a “barbecue-type get-together” at their rural home Sunday night, less than 24 hours before the bodies were found.

“He had nothing to do with the death scene or the abduction of the children,” Wolfinger said.

Lutner, a concrete worker with an extensive criminal record, contacted authorities through his probation officer after learning he was wanted for questioning, Wolfinger said.

He was the last known visitor to the rural house where the victims, Brenda Kay Groene, 40; her 13-year-old son, Slade Vincent Groene; and her boyfriend, Mark McKenzie, 37, were discovered slain Monday evening.

County Coroner Dr. Robert West said Thursday the three were bludgeoned to death. He would not say when they died or what kind of weapon was used.

An Amber Alert had been issued Tuesday for Groene’s missing children, Dylan Groene, 9, and Shasta, 8.

“Please, please release my children safely,” Steve Groene, the children’s father, pleaded in a televised statement.