BIRMINGHAM, Ala. (AP) — Investigators continue to track down information about who sent a threatening letter to a judge in Birmingham.

Emergency crews responded to the Mel Bailey Criminal Justice Center on Tuesday after the clerk’s office reported a letter containing a suspicious white powder.

Chief Deputy Randy Christian of the sheriff’s office said deputies responded with the bomb squad when the court clerk’s office reported receiving a letter with the substance and “threatening language” directed at a federal judge.

Deputies from the sheriff’s office bomb squad assessed the threat and decided it’s apparently not a health risk. The items were sent to the FBI laboratory for analysis.

The sheriff’s office along with the FBI and U. S. Postal Inspector’s Office are investigating.