BOSTON – The Massachusetts state trooper who leaked arrest photos of Boston Marathon bombing suspect Dzhokhar Tsarnaev is going back on patrol.

Sgt. Sean Murphy, who had been stationed at department headquarters in Framingham, is now assigned to the midnight shift at the Athol barracks in north-central Massachusetts, State Police spokesman David Procopio said Thursday.

Procopio said the assignment effective last week is not punishment for the unauthorized release of 14 photos, some of which showed a battered and bloodied Tsarnaev with the red dot of a sniper’s rifle scope in the middle of his forehead. “That investigation is still under way,” he said.

Murphy, a well-respected, 25-year veteran who took crime-scene pictures as part of his official duties, leaked the photos to Boston magazine last month in response to what some people perceived as an inappropriately glamorous shot of Tsarnaev on the cover of Rolling Stone magazine.

Murphy said in a statement to Boston magazine that the Rolling Stone cover photo, which Tsarnaev had posted online, was an insult and he wanted to show “the real Boston bomber.”

Murphy’s lawyer Leonard Kesten says his client is on leave because of an injury unrelated to his work and hasn’t started the new assignment.

“He’s going to go back to work. He loves the State Police,” Kesten said.

Kesten said Murphy found out about the new assignment a couple of weeks ago, but learned of the shift in media reports. As to whether the assignment is punitive, Kesten said, “You can draw your own conclusion.”

Murphy served a short suspension and was placed on desk duty last month. He maintains his seniority and will have the opportunity to bid for a different shift.

Col. Timothy Alben, the State Police commander, has said Murphy has an exemplary record and is unlikely to be fired.

Troopers assigned to the Athol barracks are responsible for patrolling the largely rural towns in the area as well as Route 2, the main east-west artery in the region.

Tsarnaev, 20, has pleaded not guilty in connection with the April 15 bombing that killed three and injured or maimed 260.