The Assopciated Press

IMPERIAL, Mo. -- An 89-year-old man fatally shot his ailing wife, then killed the couple's dog before turning the gun on himself, Jefferson County authorities said Sunday.

Investigators were trying to pinpoint why Alvin Brouk killed 87-year-old Alvina Brouk, who had an unspecified terminal illness, before committing suicide, sheriff's Lt. Rich Stevens said. A .22-caliber pistol was found at the scene in this St. Louis suburb, Stevens said.

Stevens said he had no immediate specifics about the nature of Alvina Brouk's illness, and "we don't know if that was the cause or not" of the shooting. Alvin Brouk did not leave behind a suicide note, Stevens said.

A family member checking the well-being of the couple found the bodies shortly after 10 a.m. Sunday and called authorities.