The letter from suspect Marc Harold Ramsey triggered a security scare at the Colorado campaign office on Friday and staff members were immediately evacuated.

Authorities said the envelope's return address included Ramsey's name, his inmate number and the location of the jail where he is incarcerated.

Ramsey was charged with a single count of mailing a threatening communication, a felony that carries a maximum penalty of five years in prison.

Several campaign workers went to the hospital as a precaution, and more than a dozen others underwent decontamination procedures at the scene.

Agencies