When a New Hampshire man was slapped and insulted outside South Station, he didn’t go back to his car and drive away, a Suffolk County prosecutor told a Superior Court jury this morning. Instead, Assistant District Attorney Holly Broadbent said, he went back to his car, retrieved a pistol, and executed his rival in a hail of gunfire as daylight faded on the last day of 2006.

SEAN EVELYN (D.O.B. 2/22/86) is charged with first-degree murder for shooting 20-year-old Cushings Fortuna to death on Beach Street on the afternoon of Dec. 31, 2006. Evidence suggests that the two men crossed paths at South Station that day by pure chance and that, because of some prior disagreement, Fortuna assaulted Evelyn in front of Evelyn’s girlfriend.

Evelyn suffered no physical injuries in the confrontation, Broadbent said.

“There was no black eye,” she told jurors. “There was no bloody nose.”

Moreover, Broadbent said, Evelyn’s response was far out of proportion to the level of provocation. Instead of walking away or notifying police, he returned to his vehicle, where he kept an unregistered handgun along with a quantity of crack cocaine. After sitting quietly for a moment, he grabbed the gun, proceeded to chase the victim down, and fired at least seven shots at him.

“There were other options besides going back to your Mercedes Benz, opening up a secret compartment, getting your Glock .40 caliber semiautomatic, and chasing a man down to execute him,” Broadbent said, highlighting what prosecutors allege was the deliberate premeditation that supports a first-degree conviction.

“This was calculated,” she said. “This was revenge. This was an execution.”

No passersby notified police or anyone else of the physical altercation between Fortuna and Evelyn. Multiple witnesses, however, called 911 to report a man with a gun chasing three other men and firing multiple shots at about 4:30 that afternoon. Witness reports also indicated that the gunman had gotten out of a Mercedes operated by a young woman prior to the shooting.

Boston Police obtained a partial license plate number from that report. Responding officers stopped Evelyn’s girlfriend in his car a short distance away. While executing a search warrant, detectives later discovered a secret compartment within the vehicle that contained drugs and had once contained the murder weapon.

Boston Police also recovered a series of shell casings that prosecutors say suggest Evelyn was disciplined and thinking clearly as he chased Fortuna. Single casings were found on Atlantic, while five were found grouped in the area of Beach and South streets where the victim suffered his fatal injuries.

“The defendant had the presence of mind … to wait until he chases Cushings Fortuna down Beach Street,” Broadbent said. “That’s where he fires five more times from only a few feet away. He knew exactly what he was doing – he finally had Cushings Fortuna cornered.”

After closing arguments, Judge Frank Gaziano instructed jurors on the relevant law and they began their deliberations.

Evelyn is represented by attorney John Hayes.