Signal Mountain murders
The Signal Mountain murders refers to a widely publicized case in 1988 involving the shootings of Richard Mason, Kenneth Griffith, and Earl Smock near Chattanooga, Tennessee.

Missing men
The three men had been riding the backwoods of Signal Mountain.  The men were missing and being searched for by their relatives when they did not return home. The bodies were found off Big Fork Road near the community of  Suck Creek by a resident while their all-terrain vehicles (ATVs) were found down an embankment on the side of Roberts Mill Road.

Suspect
The owners of the land were Frank Casteel and his wife, Susie. When Frank noticed more and more people intruding on his land he consulted a police officer who advised him to keep a logbook of everyone he witnessed. The men were later found dead and Casteel was a prime suspect. In 1997 Frank had a mistress, Mrs. Marie Hill. Larry Sneed had taken possession of the logbook in 1988.

Conviction
Although no physical evidence to support Casteel’s conviction, he was sentenced to life in prison. An appeal was made and eventually given an opportunity to overturn Casteel’s conviction in 2001. The attorneys said there was no hard evidence that clearly identifies Casteel as the murderer. In 2003 Frank Casteel was found guilty again for the triple homicide and returned to prison.

Death
Casteel died in prison in May 2019 at the age of 71.

In 2020, Casteel's son Franklin Trever Casteel authored a book on the subject.

Media depictions
Unsolved Mysteries aired a segment regarding the murders in season 2 episode 13 which aired on January 3, 1990.
A&E (TV channel) covered the murders in season 4, episode 9, of their City Confidential series. The title of the episode was "Dangerous Trespassing".
Investigation Discovery portrayed the murders in the show "Bloodlands" on August 18, 2014.  This was season 1 episode 3 titled "Signal Mountain Murders".

References

Murder in Tennessee
1988 murders in the United States
Crimes in Tennessee
1988 in Tennessee