Bryan Clay, 22, was arrested Friday in the April 15 rape and bludgeoning deaths of 38-year-old Ignacia Martinez and 10-year-old Karla Martinez. He had no connection to the family of five, Lt. Ray Steiber said Saturday.

"This was a complete stranger killing a mother and daughter and attacking the father," Steiber told The Associated Press. "I've been doing this (police work) 24 years, and you don't see cases like this. I can't even put this into words."

Police were notified about the case when a 9-year-old boy, who was not injured by the attacker, came to school the next day and informed a counselor that his mom and sister were dead.

Nothing was taken from the house, and investigators were unsure of the motive for the attack.

"There's no rhyme or reason to why (it happened)," he said, adding Clay doesn't have a "significant" criminal history.