GUTHRIE CENTER, Iowa (AP) — Law enforcement officials have charged an Ames man in a May house fire at Guthrie Center that killed two young girls.

The Guthrie County Sheriff's Office said in a news conference Wednesday that 26-year-old Patrick Ryan Thompson is charged with two counts of first-degree murder, two counts of attempted murder and one count of arson. It was not clear whether he yet has an attorney.

Investigators had already determined that arson caused the May 15 fire that killed 16-year-old Shakiah Cockerham and 12-year-old Melanie "Paige" Exline and injured their uncle, 54-year-old William Long III, and grandmother, 74-year-old Shirley Exline.

Investigators say Thompson is the stepson and stepbrother of men charged in a sexual abuse case in which at least one of the girls was a victim.