FARGO — A 37-year-old woman has been sentenced to six years behind bars after pleading guilty in U.S. District Court to a charge that alleged she traveled to North Dakota from Canada to obtain a chemical weapon she purchased on the dark web.

Sijie Liu of Winnipeg, Manitoba, will remain in the Cass County Jail until she can be transferred to Canada to serve her sentence, according to documents filed in North Dakota U.S. District Court.

Liu was given credit for time served since her arrest in March 2019.

According to court documents:

Liu crossed into North Dakota from Manitoba at the Pembina, N.D., port of entry on March 5, 2019.

Liu told a U.S. Customs and Border Protection officer that her purpose for traveling to the U.S. was to go shopping in Grand Forks. She said she intended to return to Canada later that day.

After crossing into the U.S., Liu drove to a commercial mail receiving agency in Pembina, where law enforcement officers in plainclothes observed Liu pick up several packages claiming her name to be Julie Chen.

Liu was arrested as she left the mail receiving business with the packages.

Court documents state Liu recently pleaded guilty to a charge of attempting to acquire a chemical weapon. In order to do that, she went to a hidden services website on the dark web, a part of the internet that is not indexed by search engines and requires special software or authorization to access. There she communicated with an undercover FBI official to obtain 10 ml of a toxin.

The type of toxin involved was not clear.

The court documents say Liu also attempted to acquire protective equipment that could be used to handle the toxin safely.

As part of a plea agreement signed in March, federal prosecutors and Liu's attorney agreed on a recommended sentence of six years, which was a downward departure from sentencing guidelines.

It is not clear from the court documents how the toxin was intended to be used.

Court documents say that after Liu was arrested and prior to authorities questioning her, she said to law enforcement officers: "I know what I did was wrong."

Later, when Liu spoke to someone she identified as her husband, she was overheard to say she had broken the law and had been arrested, court documents said.

Two other charges Liu was facing as part of a federal indictment were dismissed. Additional details regarding that indictment were not clear, as the document was one of several associated with the case that have been sealed by the court.

The U.S. Attorney's Office for North Dakota and Liu's attorney did not respond to requests for comment on Thursday.