The execution-style murders of eight members of the same family in rural Pike County, Ohio, has set residents on edge and sent investigators into overdrive as they try to find out who killed the Rhoden family members, and why.

Adding to the intrigue: the discovery of marijuana growing operations at three of the four crime scenes.

Here's what we know, and don't know, about the crimes:

The killings

What we know:

In a series of what investigators called well-planned, execution-style killings carried out at four locations, eight members of a single family were methodically shot in the head Friday while they slept in their homes about 50 miles south of Columbus.

A relative discovered the bodies.

"There's blood all over the house," the woman told 911 operators. "My brother-in-law is in the bedroom. It looks like they beat the hell out of him."

Authorities identified the victims as Hannah Gilley, 20; Christopher Rhoden Sr., 40; Christopher Rhoden Jr., 16; Clarence "Frankie" Rhoden, 20; Dana Rhoden, 37; Gary Rhoden, 38; Hanna Rhoden, 19; and Kenneth Rhoden, 44.

Authorities in Ohio released this chart tracing the relationships of the slain Rhoden family members.

Amid all the carnage, three children were found unharmed -- a 4-day-old infant who was next to her mother when she was killed, a 6-month-old baby and a 3-year-old. State authorities are now caring for the survivors.

Two of the residences where the killings took place are within walking distance, authorities said. A third is about a mile away and the fourth about eight miles away, they said.

What we don't know:

Who killed them, or why. Authorities do, however, think the killers were familiar with the victims.

"It was a sophisticated operation and those who carried it out were trying to do everything they could do to hinder the investigation and their prosecution," Ohio Attorney General Mike DeWine said.

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Marijuana grow operations found

What we know:

Extensive marijuana grow operations were found at three of the sites, DeWine told reporters Sunday.

An official with knowledge of the operation told CNN's Nick Valencia that the marijuana wasn't being grown for personal use.

An aerial view of one of the crime scenes.

"It was for something much bigger than that. It was a very sophisticated operation," the official said.

Such operations are often located indoors, and use elaborate lighting, watering and feeding systems designed to yield crops every three to four months, according to an April article in Police Chief magazine

What we don't know:

Whether the killings had anything to do with the marijuana grow operation.

The investigation

What we know:

It's likely to be lengthy.

DeWine said police have executed at least five search warrants and 50 of 60 people have been interviewed so far. Authorities have received 100 tips and 18 pieces of evidence have been submitted to the crime lab. Seven of the eight autopsies have been performed so far, he said. The last one scheduled is for Monday, said DeWine.

What we don't know:

What investigators have found or how many guns were used in the shootings.

Family warned

What we know:

Pike County Sheriff Charles Reader

Pike County Sheriff Charles Reader said he has cautioned surviving family members that they may still be in the killers' crosshairs.

"We have a specific family that's been targeted but I don't think there's been a threat to any other members of the community," he said. "I cautioned them they are a target and I cautioned them, 'Be armed.'"

What we don't know:

Exactly why the Rhoden family had been targeted -- or if it had anything to do with the marijuana operation.

Pot in Pike County

What we know:

Pike County is no stranger to marijuana problems. In August 2012, Ohio law enforcement officers found "a major marijuana grow site in Pike County with suspected ties to a Mexican drug cartel," according to a press release DeWine's office issued at the time.

Investigators destroyed about 1,200 marijuana plants and found two abandoned campsites they believe belonged to Mexican nationals, the release said.

What we don't know:

DeWine has not indicated any connection between the 2012 findings and the operations found on the Rhoden properties.