DETROIT (WWJ) - Charges could be brought against the person who sent a letter containing a white powdery substance to a judge in Detroit.

Judge Vonda Evans’ courtroom at the Frank Murphy Hall of Justice was evacuated Tuesday afternoon as Detroit police, the FBI and Homeland Security agents examined the substance.

The powder was eventually deemed harmless and “all clear” was given at the courthouse.

Investigators believe a jail inmate sent the letter to the judge and, because the letter was sent through the mail, it could become a federal case.

The investigation continues.