They were two men carrying the tools of their trade. One, 27-year-old Jeff Santiago, carried a tool belt, tape measure, and other accoutrements of his job as a construction worker. The other, JESSE CAMACHO (D.O.B. 5/7/87), carried a loaded, unregistered handgun.

“They were two men who had never even met,” Suffolk County Chief Trial Counsel Patrick Haggan said this afternoon during opening statements in Camacho’s murder trial. “They were two men whose lives crossed paths one night with devastating consequences.”

Camacho is charged with first-degree murder for Santiago’s shooting death at King Arthur’s Lounge in Chelsea shortly after midnight on Jan. 24, 2008. He is additionally charged with two counts each of armed assault with intent to murder and assault and battery with a dangerous weapon for allegedly shooting two other men – one a friend of the victim and one a doorman at the club – and unlawfully possessing the firearm with which he shot them.

Santiago, an Everett resident, had been enjoying a night out with friends, Haggan said. Camacho, who lived in East Boston at the time, was present with friends of his own. It was an altercation between individual members of those two groups, Haggan told jurors, that led to the “shooting rampage” that claimed Santiago’s life and injured the two surviving victims.

“Nothing in the evidence will suggest that Jeff Santiago did anything that led to the carnage that night,” Haggan said. “That comes down to the actions of one man – one man who was ready to arm himself with a loaded .45 caliber semiautomatic firearm, one man who was ready to put that loaded .45 caliber semiautomatic firearm into his waist or pocket, one man who was ready to take that loaded .45 caliber semiautomatic handgun into a crowded nightclub. He was ready for trouble, ladies and gentlemen – he was looking for trouble.”

Haggan told the court that one of Santiago’s friends noticed one of Camacho’s friends in the crowd at King Arthur’s Lounge that night and confronted him about a prior dispute. That escalated into a fight in which Santiago’s friend struck Camacho’s friend with a bottle.

“That’s where it should have ended,” Haggan said, “but one man took it upon himself to take that brawl one step further … He fired five shots at anybody and everybody in that group.”

Chaos erupted in the club as dancers, bouncers, and patrons scrambled for the exits, Haggan said.

“Everyone was running for their lives from that man,” Haggan said. “Not one person was coming toward him or posing any threat to him.”

Among the injured, Haggan said, was Santiago, who neither knew Camacho nor had any part in the initial conflict.

“And when Jeff Santiago fell to the floor, Jesse Camacho shot him dead,” the prosecutor said.

The Everett man died a short time later of three gunshot wounds to his chest, back, and leg. There was no question who shot him, Haggan said.

“There’s one good thing about King Arthur’s,” Haggan said. “They’ve got a lot of video cameras.”

In the aftermath of the shooting, Haggan said, Camacho fled the City of Chelsea and the Commonwealth of Massachusetts.

“Make no mistake, ladies and gentlemen,” Haggan said. “There’s only one reason the defendant sits before you today – the police departments across this country, the U.S Marshals, and the Mexican Federales who tracked him.”

Camacho was apprehended in Mexico City on Oct. 30, 2008. He was rendited to Massachusetts on March 13, 2009.

Michael Shultz is the victim-witness advocate assigned to the case. The defendant is represented by attorney Willie Davis. Judge Patrick Brady is presiding in courtroom 815 of Suffolk Superior Court.

Members of the jury are expected to visit the scene of the crime during a view tomorrow.