Authorities arrested a man for failing to register as a sex offender and then returned to his property for a shocking discovery: The bodies of two men missing for weeks were buried under a shed.

The identities still were being confirmed through autopsies Sunday, "but we're fairly confident" they are the men, Iron County Sheriff Mark Gower said.

With help from police dogs, the bodies were unearthed Saturday night, Gower said.

Chad Grijalva and Derek Davis, both 34, haven't been seen since Oct. 24. They lived in a neighboring county, Washington, here in southwestern Utah.

Gower said his deputies had no idea that a routine arrest would turn into a homicide investigation.

On Friday, they drove to the home of Martin Nelson to arrest him on a charge of failing to register as a sex offender when he lived in Washington County.

After the arrest, they obtained a search warrant to return to the property to gather evidence that he failed to register in Iron County, too. Deputies discovered marijuana — and a white Ford Ranger pickup that belonged to Davis.

"It's a very cluttered property with over 40 abandoned vehicles and outbuildings in disarray," the sheriff said.

Police dogs led investigators to a shallow grave Saturday.

Beryl is a small town in a remote area of Iron County, about 10 miles east of the Nevada border and more than 250 miles south of Salt Lake City.

Nelson, in custody, has declined to answer questions about the bodies, Gower said. He was charged with growing marijuana and is a suspect in the deaths.

The disappearances of Grijalva and Davis baffled family members because they had jobs and one of them missed a funeral.

"I know it's my son and Derek," Fred Grijalva told The Salt Lake Tribune, noting they were longtime friends.

"Hiking, camping, you name it. If it had to do with outdoors, Chad did it," Fred Grijalva said. "That's what he loved doing, that and working with the public, working with people."