A Tennessee lawmaker contends he put a digital recorder under his administrative aide's office desk in Nashville as a "prank" but a complaint has started a state investigation.

Republican state Rep. Jim Cobb of Spring City (Dist. 31) told the Chattanooga Times Free Press there was "no invasion of privacy done or intended" when he placed the device on the underside of the desk used by his administrative aide, Paul Overholser.

The lawmaker represents Rhea County and part of Hamilton County.

The aide said Friday the Tennessee Bureau of Investigation has instructed him not to comment.

Cobb told the newspaper the recorder was visible from Overholser's chair. Cobb said he was expecting them to "laugh about it."