FBI investigates Oregon white powder suspect

The Federal Bureau of Investigation has confirmed that it is investigating an inmate in Multnomah County as a possible suspect behind at least one of the recent white powder scares in Portland, Oregon.

Within the past month, six locations throughout Portland were targeted by suspicious envelopes with a powder inside that resembled anthrax. Authorities allege that Andrew Laud Barnett sent one of the letters to Stephen Peifer, the prosecutor on his case, KATU reports.

Barnett allegedly threatened the prosecutor and wrote his own name on the envelope as a return address. Barnett had previously sent two other threatening letters to Peifer. A DNA mouth swab allegedly found that Barnett's DNA matched the DNA on the envelope flaps of the powder-laced envelope.

Investigators confirmed that all six letters came from inside of the Multnomah County Jail. Barnett is already facing charges for sending other letters of a threatening nature to the deputies and sheriff of Washington County. He also faces charges for assaulting a corrections officer with urine and feces, according to KATU.

Barnett has now been banned from mailing letters or having any access to writing instruments along with having any medications that can be turned into powder. Barnett has also been transferred to the federal prison in Sheridan.