Investigators are looking at numerous avenues as a motive for the killings among them is whether there is a Mexican drug cartel connection, a possible drug turf war or a family feud.

A law enforcement source confirmed that investigators found roughly 200 marijuana plants growing inside one of the four crime scenes where eight people were killed Friday in Pike County.

The source said the size of operation indicates it was being grown for sale, not for personal use.

A second law enforcement source said that investigators are looking at numerous avenues as a motive for the killings among them is whether there is a Mexican drug cartel connection, a possible drug turf war or a family feud.

The Pike County Prosecutor said investigators also found two marijuana crops growing outdoors.

Each plant could produce about one pound of marijuana. A pound of high grade quality marijuana has a street value of about $2,000.That means the marijuana grow operation could have a value of a half million dollars, or more.

Ohio Attorney General Mike Dewine described the murders as pre-planned and cold blooded.

“Those who carried it out were trying to do everything they could do to hinder the investigation and their prosecution,” DeWine said.

Investigators are hopeful the killer or killers made mistakes. Crime scene investigators spent days scouring all four crime scenes.

DeWine says 18 pieces of evidence are now under the microscope at the Bureau of Criminal Investigation's crime lab.

10TV was inside the lab last year where forensic experts demonstrated even the most microscopic traces of DNA can produce a sample viable enough to enter into a nationwide DNA database of known criminals.

Last year the BCI lab also showed 10TV forensic abilities to match microfibers or partial shoe prints to a suspect's clothing.

If investigators make an arrest, each tiny piece of evidence gathered at the crime scene could become a critical piece of the puzzle.