SALEM – The trial of Jose Cabrera, charged in the fatal shooting of a rival gang member on Halloween night of 2008, is expected to end on Monday.Cabrera, 20, who last lived at 3 Chestnut St., in Lynn, is charged with the fatal shooting of Tony Pich, 22, who was gunned down from a single bullet from a .357 revolver in front of his home at 1-3 Olive St., on Nov. 1, 2008.Cabrera has insisted that the commonwealth have the wrong person and that someone else fired the fatal shot.Assistant District Attorney Kristen R. Buxton will end her case early Monday morning, then defense lawyer Jeffrey T. Karp will lay out his theory of the case.It is not known if Cabrera will take the stand in his own defense.Buxton maintains that Cabrera, who was just age 18 at the time of the incident, was a member of the Deuce Boyz gang and that Pich was a member of AKC (Avenue King Crips.)State Trooper Richard Haselton, a firearms expert testified Friday as the trial ended its fourth week of evidence.Haselton described the different projectiles found at the scene of the crime at 1-3 Olive St., and that he believed three spent projectiles found in the wall at Olive Street home were from what is referred to as a 39 caliber class which takes in such handguns as a .357, a .380 and a 9mm revolver.Pich was gunned down from a single bullet to his chest from a .357 revolver that ripped through his left side, fracturing his ribs and perforating his vital organs which caused massive internal bleeding and organ malfunction killing him.He also described that the other projectiles and bullets found at the scene were probably from a 9mm and .25-caliber handgun. Two guns were seized by police in the Olive Street home, a 9mm and a .25-caliber during their investigation.Lynn Police Lt. Michael Vail, who is head of the gang unit in Lynn, also testified describing the different gangs, colors they wear and the code they go by.?Are you familiar with their Codes of Conduct,” asked Buxton??Yes,” Vail replied, “no one talks to police. No one wants to be a rat.”He described to the 16-member jury panel how each “sect” of gangs have what is referred to as a charter. They have meetings, ranks and laws, he said.You start out being a Soldier and then when you reach a certain rank you become a Deuce Boyz, a sect of the “Bloods,” gang.?If someone does talk to police what can happen,” Buxton inquired.?They can be killed,” replied Vail.Judge David A. Lowy said he expects to have closing summations on Tuesday morning and then he will instruct them as to the law regarding the charge of first-degree murder.