The discovery of six potentially poison-tainted envelopes shut down the Pine County Courthouse in Pine City Tuesday, the Duluth News Tribune reports.

The emergency halted the first day of testimony in the trial of a Duluth police officer accused of assault.

Pine County sheriff's officials cleared the facility about 1:45 p.m. Tuesday when the envelopes, which contained an unknown, white powdery substance, were delivered to several departments. At 3:30 p.m. a hazardous materials team from the St. Paul Fire Department responded to the call.

Northland's News Center says the team is examining the substance, and it was unknown whether the trial would resume Wednesday.

According to the News Tribune, officials wouldn't say whether the incident was related to the trial.

Officer Richard Jouppi is accused of fifth degree assault and disorderly conduct in the case, over an on-duty incident with an intoxicated man at the Duluth Detoxification Center on Sept. 21.

The case has drawn attention because the alleged victim in the case, 50-year-old Anthony Jon Jackson, was in a wheelchair at the time of the videotaped confrontation.

The News Tribune reports Jouppi's attorney requested the case be moved from Duluth to Pine City, partly because it reduce the public safety risk.

The Ramsey County Courthouse in St. Paul was shut down last month after an envelope with a white powdery substance was found.

Tests on the substance found at the Violations Bureau office at the courthouse deemed the material to be harmless.