MADRAS, Ore. -

A telephoned bomb threat prompted evacuation of the Jefferson County Courthouse for about an hour Monday morning, but a search turned up no problems, Sheriff Jim Adkins said.

An unidentified male caller prompted the evacuation from about 8 to 9 a.m., Adkins said.

The building was searched by the court security deputy, county maintenance and Madras police, but "nothing was found," the sheriff said, adding that the investigation is continuing.

Just recently, the FBI arrested an Ohio man, Lonny Bristow, in their investigation of bomb threats made to courthouses and other public buildings in five states, including Oregon, late last year. Officials after the recent arrest gave no immediate indication of a possible motive.

Deschutes, Crook and Jefferson counties were among the 28 hit by the called-in threats.