Four family members have been charged with murder in Ohio, following the deaths of another family of seven and one other person.

The eight victims, who lived across three homes, died in April 2016 with each one suffering an “execution-style” single bullet wound to the head, many of them while they were asleep.

Reuters reports that they included Christopher Rhoden Sr, 40; his ex-wife, Dana Rhoden, 37; and their three children, Hanna, 19, Christopher Jr, 16, and Clarence, 20.

The accused are George “Billy” Wagner III, 47, his wife Angela Wagner, 48, and their sons, 27-year-old George Wagner IV and 26-year-old Edward “Jake” Wagner, who have each been charged with eight counts of aggravated murder.

Announcing the charges, Pike County Sheriff Charles Reader said the family “conspired, planned, carried out and then allegedly covered up their violent act to wipe out members of another family”.

“They did this quickly, coldly, calmly and very carefully. But not carefully enough,” he added.

“They left traces. They left a trail: The parts to build a silencer, the forged documents, the cameras, the cellphones, all that they tampered with, and the lies, all the lies they told us.”

Three other victims were Christopher Sr’s brother, Kenneth Rhoden, 44 and a cousin, Gary Rhoden, 38. The only one not biologically related to the family was Clarence Rhoden’s girlfriend, 20-year-old Hannah Gilley.

Three small children, including a six-month-old baby and a three-year-old, survived the killings.  

If found guilty, the Wagner family could face the death penalty.

Ohio Attorney General Mike DeWine has hinted that the motivation for the killings could have been a battle over the custody of a child.

“There certainly was obsession with custody, obsession with control of children,” he said. “This is just the most bizarre story I’ve ever seen in being involved in law enforcement.”