FBI thinks Oregon powder scares have been curbed

FBI officials say that they have halted a series of threatening letters containing white powder, though no comment was made on whether or not an arrest had been made in the case.

The bureau assured the public that the white powder inside the envelopes delivered to multiple Portland, Ore., locations is harmless. Tests have shown the substance to be non-toxic. Despite the fact that the powder is not a biological agent, anyone responsible for the threats would face up to 10 years in prison for mailing a threatening communication and up to five years for the hoax, KATU reports.

"The FBI and its local partners believe they have stopped the sender or senders' ability to continue this stream of threats," Beth Anne Steele, an FBI spokeswoman, said, according to KATU.

The most recent Portland threats occurred on Thursday when a letter was found in the Market Center building near Market Street and Southwest Fourth Avenue and another was found at the Marquam Plaza Building on Southwest Third Avenue.

Two additional envelopes were found on Wednesday and two more on Thursday. The FBI is investigating white powder incidents that occurred at the Mark O. Hatfield Federal Courthouse on April 26 and the Lloyd Center Mall on Tuesday.

In all of the incidents, the envelopes were addressed to human resources offices and had the term anthrax written in a two page letter in the envelope or directly on the envelope.