Two inmates at the Montana Women’s Prison are facing charges after prosecutors say they worked with a “low-level” California dealer to get drugs into the prison.

Angelene Victoria Tropp, 31, and Heather Christine Byerly, 43, both face a single count of transferring illegal articles, a felony. The charge carries a maximum of 10 years in prison. Both women pleaded not guilty Feb. 1.

Department of Corrections investigators opened an investigation in October 2016 when another, unnamed inmate reported that Tropp had been receiving drugs through the mail, according to charging documents. Tropp was getting it in the form of Suboxone strips pasted onto envelopes and covered with a postage stamp, as well as liquid meth sprayed onto pages of paper inside the envelope.

DOC investigators began listening to Tropp’s phone calls. From October 2016 through February 2017, Tropp made a series of calls to a California man, Duncan Brady, who shipped her the drugs, according to charges. Police in Costa Mesa, California, told Montana investigators they believed Brady was a low-level dealer who sold meth, heroin and pills.

Byerly, the other inmate, coordinated with a man named Doug Kirby, who is identified as her friend and former employer, to arrange for the California dealer to be paid through money orders.

In a statement to investigators in March 2017, Byerly said Tropp promised her she would get hobby supplies if she arranged the money order, and that it wasn’t until after the order was sent that Tropp told her she’d get drugs in exchange.

Tropp declined to speak with authorities. Kirby denied knowledge that the payment was for anything other than hobby supplies.

Tropp was set to leave the women’s prison soon. Her five-year sentence for possession with intent to distribute expires Feb. 21. Byerly is serving 10 years for a fourth or subsequent DUI with excessive alcohol content.

The drug case against Tropp and Byerly is the first under a new process for reviewing women's prison cases, according to DOC spokeswoman Judy Beck. The DOC's Investigations Unit is now sending its investigations directly to the Yellowstone County Attorney's Office for possible prosecution, rather then referring them first to the Billings Police Department for review. The change was requested by BPD.