PORTLAND, Ore. (AP) -- A Tillamook County man has admitted sending numerous threatening letters containing fake anthrax powder to state and federal government offices over a period of nearly

three years, federal court papers released Friday show.

The documents say David Albert Groves, 48, of Bay City, admitted sending numerous letters containing a powdery substance as well as threats to government agencies, private businesses and at least one individual.

He is charged with mailing threatening communications. U.S. Magistrate Judge John Acosta assigned him a public defender and released him, setting an arraignment May 30.

Groves told an FBI agent that he mailed more letters than he could remember, court papers show.

An FBI affidavit said DNA results traced some of the letters to Groves, and the handwriting on many seemed to be the same. Some letters are still being examined.

The affidavit said a letter arrived at the Federal Deposit Insurance Corporation in Washington, D.C., on May 31, 2005, containing a threatening message and a powder "which could not be visually ruled out as containing anthrax."

The powder, contained in a smaller interior envelope, tested negative.

Court papers noted that in October 2001 letters were mailed that did in fact contain Bacillus anthracis, which causes the anthrax disease, resulting in several deaths.

On June 6, 2005, a letter with powder arrived at the Bureau of Alcohol, Tobacco, Firearms and Explosives in Hyattsville, Md., containing an obscene wish that the recipient die and indicating that the sender had "lots more stamps and there's plenty of people that I would like to give them a piece of mind." It was signed "Beezulbub."

Both bore a Portland address and postmark as did many others, the affidavit said. Many of the return addresses proved bogus, and four bore the names of famous pirates, although the affidavit didn't specify which pirates.

While the powder in the June 6 letter also tested negative, the affidavit says it shut down the BATFE's mailroom for some time.

That Oct. 20 a third letter arrived at the BATFE "containing an overtly threatening letter" stating "check for prints I made sure they were all over," an oversize simulation of U.S. currency and a statement saying "I'm going to kill as many of you ... as I can" and signed, "Love, Beezulbub." The date "9-11" appeared on the corners and in the center of the simulated currency.

On Oct. 31, 2005, a similar letter with a powder and a "Deception Dollar" was delivered to a branch of US Bank in Gresham with another angry, obscene message wishing death on the recipients. The envelope carried the logo for a motel in Bend.

Similar letters containing angry statements and power arrived at the offices of the Oregon Department of Fish and Wildlife in Salem, the Northwest Oregon Housing Authority in Warrenton, the Oregon Department of Revenue and the Oregon Coalition Against Domestic and Sexual Violence.

The affidavit said letters deposited in Tillamook, near Bay City, are postmarked and processed in Portland.