A Boston Police detective has been sentenced for interfering with an FBI investigation involving a violent narcotics trafficking gang, authorities said.

Brian Smigielski, 43, of Norton, pleaded guilty in September to one count of conspiracy to defraud the United States during the course of a federal investigation. During sentencing this week, he received one year of probation and a fine of $5,000.

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According to the U.S. Attorney’s Office for the District of Massachusetts, from early 2009 to 2011, the FBI and Boston Police Department were conducting a joint investigation into the Academy Homes Street Gang, which operated out of the Academy Homes housing development in Roxbury.

Smigielski was the lead investigator during its initial stages and “became upset after being ordered to turn over the investigation to the FBI and other BPD units,” a statement from the U.S. Attorney’s Office said. 

In, 2010 and 2011, Smigielski conspired with a fellow Boston Police officer and AHSG gang members to hinder the investigation, including informing members of the pending investigation and warning them of impending arrests.