The suspicious white powder that shut down a Naugatuck building last month and prompted authorities to close a pizzeria was simple table salt, the Republican American reports.
The substance was mailed to a woman at 123 Cherry St. on July 28.
During their investigation, police evacuated the building, which includes a pizzeria and an apartment above it.
The Naugatuck police and fire departments contacted state officials, who in turn handed the investigation over to the Federal Bureau of Investigation.
Naugatuck Police said the F.B.I. and the state Department of Public Health informed them on Thursday that the powder was salt, the Republican-American reports.
Police spokesman Lt. Robert Harrison said the envelope containing the powder had a return address on it.
Detectives are now trying to determine if the sender intended to harass or frighten the woman.