Christopher Luciano, 23, pleaded guilty Tuesday to theft and related charges.
Sentencing is set for June 7th.
Prosecutors say Luciano and fellow officer Sean Alivera pulled over a man in October and took $3,000 from his vehicle before driving him to a police station for processing.
Authorities say a minivan then pulled up, removed 20 pounds of marijuana from the car and drove away.
Alivera is due in court Wednesday.