Three marijuana growing operations were found on the premises of at least one of the homes where eight members of the same family were killed in a small town in southern Ohio last week, law enforcement officials said Sunday.

Eight members of the Rhoden family between the ages of 16 and 44 were killed in four different homes in Piketon, Ohio, in what Attorney General Mike DeWine called a “preplanned execution” at a news conference on Sunday.

One of the victims, a woman, was killed while she slept as her 4-day-old baby lay, unharmed, in the same room, law enforcement officials said.

Dan Tierney, a spokesman for Mr. DeWine’s office, said that sheriff’s deputies discovered the marijuana operations during a search of the four homes and nearby wooded areas. Video broadcast by WCPO, a local television station, showed investigators walking through woods and searching a ramshackle shed.