COLUMBUS, Ohio — Attorney General Mike DeWine said Sunday the slayings of eight family members in rural Ohio “was a preplanned execution” and he expects the investigation will be lengthy.

The Friday killings at four different homes near Piketon was “a sophisticated operation,” DeWine said at a news conference in the small community that has been on edge since the seven adults and one teenage boy were found shot in the head.

“This was very methodical. This was well planned. This was not something that just happened,” said Pike County Sheriff Charles Reader, noting most were targeted while they were sleeping.

Authorities have been scrambling to determine who targeted the clan and why. Investigators have interviewed more than 30 people in hopes of finding leads in the deaths.

The victims were identified Saturday as 40-year-old Christopher Rhoden Sr.; his 16-year-old son, Christopher Rhoden Jr.; 44-year-old Kenneth Rhoden; 38-year-old Gary Rhoden; 37-year-old Dana Rhoden; 20-year-old Clarence “Frankie” Rhoden; 20-year-old Hannah Gilley; and 19-year-old Hanna Rhoden.