The Suffolk County Grand Jury today returned a nine-count indictment charging a Hyde Park man with the attempted murder of three Boston Police officers during a drug arrest this spring, District Attorney Daniel F. Conley announced.

The indictments charge JOHN MENTOR (D.O.B. 4/13/86) with three counts each of armed assault with intent to murder and assault with a dangerous weapon, as well as single counts of unlawful possession of a firearm, unlawful possession of ammunition, and unlawfully carrying a loaded firearm, all stemming out of an April 13 incident near the intersection of River Street and Gordon Avenue.

“The evidence does not suggest shots fired in the heat of a chase,” Conley said. “The evidence suggests a cold-blooded decision to shoot and kill Boston Police. But for the defendant’s bad aim and the officers’ immediate response, this could have been a multiple homicide.”

Mentor remains behind bars on the half million dollars’ cash bail set at his April 14 arraignment in West Roxbury District Court. Today’s indictment moves the case to Superior Court, where a second arraignment will be scheduled within the next two weeks.

On the night of the incident, two members of the Boston Police Drug Control Unit were conducting surveillance in the area of River Street, which had recently been plagued by drug-related crime. In the course of their activity, the DCU officers observed a green Honda Accord with a revoked registration. Inside were four occupants, including the defendant, who sat in the right rear passenger seat.

The DCU officers requested a marked cruiser to effect a motor vehicle stop on the Accord. A cruiser occupied by two uniformed Boston Police officers responded and stopped the vehicle.

The uniformed officers and DCU officers approached the car to ask the driver for her license and registration. As they did so, prosecutors allege, Mentor produced a gray revolver and fired it through a partly-open right rear window at the officers. Another officer returned fire. No one was hit.

The officers dove bodily into the car and prevented Mentor from firing again. They extricated him from the vehicle and placed him on the ground, where he allegedly told officers “I should have killed all three of you motherfuckers.”

At Mentor’s district court arraignment, Assistant District Attorney Mark Hallal said Mentor was on probation for a 2006 stabbing to which he pleaded guilty in 2007. Prosecutors in that case recommended a three-year state prison sentence followed by probation; he was sentenced to two and a half years in a house of correction followed by probation.

Mentor is represented by attorney Thomas Karp.