Neighbors in Milton woke up Tuesday morning to find a house destroyed by fire. But police believe the couple inside were already dead, and investigators call the couple's son a suspect in their deaths.
The son is listed in critical condition at UW Hospital.
Investigators say they recovered rifles from the home.
But they cannot say whether one of them is a murder weapon.
It happened in Milton, where the case brings to people's minds this family's tragedy more than 20 years earlier.
"I was sound asleep and I heard that noise," neighbor Fran Dimmig says.
A boom loud enough to wake up people in the quiet Milton neighborhood.
"I just figured it was the railroad down there, railroad cars," Dimmig says.
But Dimmig discovered the next morning what happened has more far reaching effects.
"I believe people as far away as three blocks heard and felt the explosion," Lt. Bill Harper with the Rock County Sheriff's Department says.
Investigators combing the home for clues say a next door neighbor reported a house fire on Ansley Avenue around 11:30 Monday night.
Police arrived within a couple of minutes to find 22 year old Daniel Kerr in the yard -- on fire.
"He made some general statements before he became incoherent that his parents were inside and were deceased prior to the fire," Lt. Harper says.
Investigators say Kerr also revealed gasoline caused the house to go up in flames.
"It's not that unusual when someone starts a fire using gasoline that they themselves are burned," Lt. Harper says.
Investigators later recovered the bodies of Kevin Kerr and his wife, Edie, in a bedroom. Kerr spent 18 years as head custodian at Milton High School. A statement from the district says, "he was an incredibly hard worker and was well liked and respected by peers."
Dimmig was one of those peers, working alongside Kerr in maintenance for the district.
"He was a real nice guy, real nice guy," Dimmig says.
But the family already has suffered its share of heartache. The Kerr's 7-year-old son David died at school in 1983 when a TV cart tipped while he was pushing it. Dimmig says, "it was real bad."
It happened at Milton West Elementary. The school sits directly behind the Kerr's home -- now the scene of another painful search for answers.
"We haven't been able to talk to him obviously, so we're somewhat at a loss for what the motive might've been," Lt. Harper says of Daniel Kerr.
Investigators say Daniel Kerr is a student at UW Whitewater. He's in critical condition at UW Hospital. An autopsy on his parents is scheduled for Wednesday morning. The Kerrs also have a daughter who lives in Waukesha.