Stephanie A. Costanzo got a break earlier this year when a federal judge gave her three years' probation.
Four months later, the former Niagara Falls police officer is going to jail for violating that probation.
Costanzo, who was convicted for allowing her drug-dealing boyfriend to store crack cocaine at her home while she was on the force, was arrested again. Probation officials say a search of her home resulted in allegations that she was hiding a known felon.
Assistant U.S. Attorney Joel L. Violanti said the felon, Stephon Hilson, has convictions for rape and assault.
"I find this to be very dangerous," U.S. Magistrate Judge Michael J. Roemer said Monday. "This could have gone wrong in many different ways."
Costanzo was jailed pending an Oct. 3 hearing to determine her sentence.
Correction: An unrelated photograph of two NFTA officers was incorrectly displayed with an earlier version of this story. It has since been removed.