Boise police will tell you that criminal gangs exist all over the Treasure Valley. The ones that seem the most visible are regional versions of West Coast gangs such as the Nortenos or Sorenos (north side or south side).It’s not uncommon to see a steady stream of gang members charged in federal and state courts on gun and drug charges.

The case of the “Slayer” gang is different. It started with a tip to Boise police last summer about a violent new group that liked to use guns and was becoming infamous for brazen robberies.

The Boise police gang unit began working with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives on the case. By March the agencies searched two homes and the Ink Spot tattoo parlor looking for guns and drugs. By June they charged 11 people — police say all 11 are connected to the Slayer gang — with a variety of violent crimes, including robbery, extortion, recruiting gang members and aggravated assault.

Just last week, the man who police and prosecutors say was the gang’s leader, 53-year-old Jerry Brown, pleaded guilty to three charges: aggravated assault, recruiting a gang member and use of a deadly weapon in the commission of a crime.

As part of a plea deal, Ada County prosecutors dropped a charge of marijuana delivery.

The plea agreement also calls for Brown to receive a 15-year prison sentence; he can’t ask for parole until he serves at least five years.

The agreement is a “Rule 11,” which means 4th District Judge Lynn Norton has agreed to the sentencing terms already.

The deal also says Brown will admit during sentencing that he was the “president” of the Slayer gang and that he recruited people to join. The deal does not require him to testify against any others, including his son, 24-year-old Damien Brown.

If any of his co-defendants calls Jerry Brown to testify and he “differs significantly” from what police reports or other evidence show, the deal will be rescinded, according to court documents.

When asked last week by the judge why he was pleading guilty, Brown said “because I (did) recruit new members for the Slayers and they do engage in criminal activities, your honor.”

For example, Brown admitted to threatening a confidential informant with a handgun in February, telling that person that if they introduced any undercover police officers to any gang members, “violence was imminent.” Brown admitted to putting a bullet in the chamber of the gun while doing this, according to court records.

Two other defendants have entered guilty pleas. If the case of the remaining eight goes to trial as scheduled on Oct. 22, all eight men will be in the courtroom with different attorneys.

VIOLENT GANG

“We didn’t know about them until last year, and we figured out pretty quickly they were one of the most organized gangs I’ve ever seen,” said Sgt. Jeff Basterrechea, who supervises the Boise police gang unit, earlier this summer. “They had rank (leadership), a structure, a system of picking victims ... and they were committing robberies. And the more they did it, the more brazen they became.”

Basterrechea and former Ada County Deputy Prosecutor Chris Atwood, who was prosecuting the case until he got a new job earlier this summer, both said the case is unique in that all members of the gang were arrested and taken into custody about the same time. An Ada County grand jury indicted all 11 connected to the gang in April. Most are being held in the Ada County Jail, but some have posted expensive bonds to get out until a trial can begin.

Boise police officials say the BPD Swat Team and ATF teams served warrants at the tattoo shop and residences — one at 1402 Broadway Avenue, one in the 1300 block of Longmont Avenue — around 5 a.m. April 3 as part of their investigation into the Slayer gang.

Officials say that officers seized guns, but they will not provide any more details.

Federal prosecutors say the ATF search warrant information — which would explain why police believed the Slayer gang had drugs and guns and what they actually found at those three addresses — remains sealed in federal files, even though that information was used to charge all 11 defendants.

BROWN’S DEAL

Another portion of Jerry Brown’s plea agreement is that the U.S. Attorney’s Office has agreed not to pursue any federal gun charges against him, according to court documents. His sentencing hearing is scheduled for Oct. 25 — just three days after the jury trial for the rest of the Slayers is supposed to begin.

What is still unclear is who the victims of the Slayers were. Because the case was taken to a grand jury, there are no probable cause documents to examine. Charging documents have names of victims, but do not say how those people were chosen.

The indictments do describe one particular attack on a man in November 2011.

According to court records, at least one suspected gang member, Devin Montgomery, met with a male victim “under the guise of purchasing a car” and then punched the victim in the head.

Two days later, prosecutors say two other gang members — Anthony “Kalani” Storch and Harry Storch — called the victim and demanded $50,000 in cash or they “would kill his friends, bosses, girlfriend, family.” They told the victim to drop off the money at a local restaurant. Court documents say some of the Slayers discussed this mission with Jerry Brown.

Indictments also mention instances of gang members battering other people, selling marijuana and conspiring to commit crimes.

Patrick Orr: 377-6219, Twitter: @IDS_Orr