Confessed murderer Mark Hofmann may face federal charges for allegedly threatening state Department of Corrections officials and a man who testified against him, a Salt Lake City television station is saying.

KSL-TV reported Thursday that law enforcement officials intercepted approximately 30 letters written by Hofmann containing the names and addresses of three people, including two members of the Board of Pardons, which denied him a chance at early parole, and George Throckmorton, a key prosecution witness in the case.The station said it took several weeks to figure out what the letters said because they were written in code.

Hofmann pleaded guilty to two counts of second-degree murder and two counts of theft by deception in the Oct. 15, 1985, pipe bomb deaths of Steven F. Christensen, 30, and Kathleen Webb Sheets, 50.

Authorities said the killings were done to cover up a scheme involving forgeries of early Mormon Church historical documents.

The station said that information in the letters apparently confirms evidence gathered from prison informants, who reportedly told authorities that Hofmann has bragged that he intends to have certain people harmed or killed.

Authorities doubt that Hofmann has the resources to hire people to commit murder, but they said they are taking the threats seriously, the station reported.