According to the Seattle Times, 64-year-old Charles Alan Wilson made several vulgar calls to Murray's Seattle office over the last few months, criticizing her for supporting healthcare reform. That vulgarity eventually escalated into death threats, police reports state.

"I hope you realize there's a target on your back now," Wilson reportedly said in once message. "Kill the [expletive] senator! I'll donate the lead."

Murray's office would not comment on the incident because of an ongoing investigation.

More from the Seattle Times:

In several other vulgar and profanity-laced messages left over the next week, the caller repeatedly threatened the Democratic senator's life and said he "hopes somebody kills" President Obama as well, according to portions of transcripts in the complaint

The FBI obtained the phone number that coincided with the calls through a search warrant served on Verizon. Another agent called the number, posing as a representative of "Patients United Now," a group that has called for the repeal of the Health Care Reform act, and identified Wilson by his voice, according to the charges.

The agent notes the timing of the threats corresponded to the passage of the health-care bill and in several of the messages, the caller "expressed his strong disapproval for the health-care reform legislation, and the fact that Senator Murray voted in support of the bill."