The slayings in rural southern Ohio were "a pre-planned execution" and the investigation is anticipated to be lengthy, said Ohio Attorney General Mike DeWine over the weekend.
All eight autopsies have been completed at the Hamilton County Coroner’s office, DeWine said in a press release.
A memorial fund has also been established for the family. Donations to The Rhoden Memorial Fund can be made at any Fifth Third Bank, according to DeWine.
Pike County Sheriff Charles Reader said most of the victims were targeted while they were sleeping.
"This was very methodical. This was well planned. This was not something that just happened," he added during a weekend news conference.
Authorities have refused to discuss many details of the crime, including any evidence or the search for a suspect or suspects.
DeWine said that investigators did find marijuana growing operations at three crime scenes.
It's not the first time authorities have found marijuana growing in Pike County, CNN reported. In August 2012, DeWine issued a press release saying law enforcement officers found "a major marijuana grow site in Pike County with suspected ties to a Mexican drug cartel."
Investigators destroyed about 1,200 marijuana plants and found two abandoned campsites they believe belonged to Mexican nationals, the 2012 release said.
DeWine has not indicated any connection between the 2012 findings and the operations found on the Rhoden properties.
Anyone with information on this case is asked to call 1.855.224.6446 or the Pike County Sheriff’s Office at 740.947.2111.