Police in Las Vegas are seeking a person of interest in connection with a threatening note addressed to Republican U.S. Sen. Dean Heller. Wednesday police released surveillance video showing the man walking around a building and getting into an elevator. The man is described as Caucasian and in his 50s. Police found the note while responding to a burglar alarm at Heller’s building, but say neither the building nor Heller’s office was burglarized. Police have not released the contents of the letter.