A preliminary test on the scene showed the substance to be sodium bicarbonate — baking soda, according to Assistant Chief Jan Snyder of the Santa Fe Fire Department. However, it was sent to the Department of Health for further tests.
County officials announced that the courthouse, Sandoval Street and Montezuma Avenue, will be closed for the rest of the day.
Authorities say the letter found about 9 a.m. at the courthouse was addressed to state District Judge Stephen Pfeffer.
Santa Fe County Sheriff Robert Garcia said 19 courthouse workers who may have been exposed to the substance were isolated while it was tested.
The rest of the court’s employees were sent home.
The FBI is investigating the situation.
The evacuation Wednesday morning comes two days after the fourth floor of the state Capitol was evacuated when what turned out to be a harmless substance was found in mail to Gov. Susana Martinez.