A Tennessee couple who "defriended" a woman on Facebook were murdered in their home by the jilted woman's father and another man, US police said.

"It's the worst thing I've ever seen," said Johnson county sheriff Mike Reece, who has worked in local law enforcement for 27 years.

"We've had murders, but nothing like this. This is just senseless."

He said Billy Clay Payne Jr and Billie Jean Hayworth were killed last month after they deleted Jenelle Potter, the daughter of one of the suspects, from their "friends" list.

Both were shot in the head and the man had his throat cut.

The couple's eight-month-old baby was in the mother's arms, unharmed, when the bodies were found.

Marvin Enoch "Buddy" Potter Jr (60) and Jamie Lynn Curd (38) were each charged in Mountain City in northeastern Tennessee with two counts of first-degree murder.

The men were arrested on Tuesday.

The case was not the first involving violence linked to Facebook.

Last year in Iowa, a woman was arrested on accusations of setting fire to a friend's garage after she was “defriended” on the social network site, local media reported.

In Texas, a man was accused of hitting his wife after she failed to "like" a Facebook post he wrote about the anniversary of his mother's death, according to media reports.

Curd's attorney, RO Smith, an assistant public defender, said of the Tennessee case that it was "safe to say there's more to it than the Facebook problem, it appears."

Reuters