Being sent to prison for life without parole did little to slow the criminal enterprises of Lamonte Martin, a 17-year-old gang leader convicted of executing another teen in an alley.

For nearly three years, prosecutors charged Monday, he masterminded a network of intimidation against witnesses in and out of prison.

Witnesses to the 2006 murder were repeatedly beaten up and threatened. One person had his neck slit. Another was told his children would be killed if he didn't recant trial testimony. Martin's mother and his associates paid or promised thousands of dollars in bribes.

The charges filed Monday against Martin and 10 more people, mostly gang members or prison inmates, described one of the most complex intimidation plans that Minnesota police and prosecutors say they'd ever seen.

"You always would hear a rumor or two of somebody trying to get a witness to recant," said Minneapolis Deputy Police Chief Rob Allen. "This case presented chilling facts. It was frightening the steps he was taking to get what he believed was justice."

A two-year investigation started after Minneapolis police and special investigators from the state Department of Corrections were working on a case unrelated to Martin's situation. Investigators pieced together letters and telephone calls from Martin, now 24, other inmates and people outside of prison. They also found that some inmates were researching an appellate case in the prison law library that also involved witnesses recanting testimony in a gang murder.

When police realized what was going on, "At first, witnesses [who were being intimidated] wouldn't talk to us because they wanted to try and handle things on their own," said Cari Gerlicher, director of the state correction special investigation office. "Thousands of hours were spent on this case."

According to the charges against Martin, police were called in September 2010 by the family of one of the witnesses, who was in prison. They said the witness and his brother, who was in another prison, were being threatened to sign affidavits by members of Martin's gang, the 19 Dipset, and other gangs. The witness' brother told police he was afraid the gang members were going to kill him or that he would have to kill them in self-defense.

Witness' children threatened

Another witness received a typed affidavit from Martin, and was told by inmates he would be stabbed and that his children, 6 and 4, would be killed if he didn't sign it.

Other allegations against Martin included a $10,000 bribe to one of the witnesses. A letter to yet another witness talked about payment for recanting and warned that he needed to "stick to the script." The letter referred to the witness "being taken care of" and said he should let Martin's associates know when he was going to court.

At one point, investigators met with a man that Martin had ordered to fight with one of the witnesses. When advised they wanted to talk to him about tampering in Martin's case, the man laughed and said, "What are you going to do to me? I have life [in prison]."

Martin's mother, who was arrested and is to be charged Tuesday, allegedly helped Martin with his plan. A case manager for a health home care business, she allegedly took $500 from a vulnerable adult and had it put in a witness' prison account as a bribe, according to the charges against Martin.

At least three witnesses signed affidavits, several of which were filed in court by Martin's attorney, stating that they wanted to recant their testimony or had lied during the trial. Hennepin County Attorney Michael Freeman said there wasn't any evidence to file a charge against the attorney. He added that corrections officials and police are "going to great lengths" to protect the witnesses.

Martin needed the affidavits after his appeal was denied by the state Supreme Court in October 2009. His motion for "post-conviction relief" was denied last December by Hennepin County District Judge Marilyn Rosenbaum. The court found that the affidavits presented as a basis for the motion carried "no indicia of reliability." That ruling was appealed and taken under advisement by the state Supreme Court last month.

Ruling prompts case review

In light of a ruling this past summer by the U.S. Supreme Court that life without parole for juveniles amounts to cruel and unusual punishment, Minnesota is now reviewing the cases of seven juveniles facing such sentences, including Martin's. He was convicted in 2007 for the killing of 19-year-old Christopher Lynch, who prosecutors say wasn't a gang member and had begged for his life before he was shot more than a dozen times in 2006.

Martin has now been charged with 12 new felony counts, including bribery, witness tampering and crimes committed in association with a criminal gang.

David Chanen • 612-673-4465