Over a five-year period, Alex Garcia and Mike Knox got to know each other well. Unfortunately, most of their conversations always took place in a patrol car on the way to the police station.

At the time, Garcia was a juvenile delinquent and Knox was a founding member of the Houston Police Department's Westside Gang Task Force. The two had little in common until Garcia - who was in a gang from ages 14 to 19, finally heeded Knox's advice and gave up his involvement in gangs.

Now they have a lot in common - both spend considerable time talking to students and others about the danger of gangs.

Knox, a nationally recognized gang expert, travels to schools teaching students how to avoid gang life. Knox, who worked 15 years for HPD before leaving in 1995, also has written a handbook to teach parents, teachers and community members about the psychology and infrastructure of gangs.

Garcia, 25, works as a mechanic and does his talking about gangs informally. His classroom is the parking lot at his apartment complex, where he tries to convince young people that they might end up in jail or dead.

Garcia gives pretty much the same advice Knox has been giving to more than 500,000 youths since 1995. Backed by sponsor Sonic Drive-ins, Knox is visiting area schools to try to demystify gangs in the eyes of the students.

He uses a demonstration to illustrate how gangs promise to "watch your back."

He has students stand behind a volunteer to illustrate what it means to "get your back." Then it becomes apparent that no one is protecting their front.

Knox said he does this to show students that gangs cannot deliver on their promises to keep them safe, to respect them and to make them belong.

He also gives presentations to teachers. Recently, he told Katy Independent School District teachers that they should not overreact to students who are in gangs. If a student stands up in class and uses profanity, the teacher should let him finish and when he sits down, critique his grammar. If a teacher sends the student to the principal's office, the student is getting what he wants, he said.

Mothers and fathers, however, also have an impact on their child's choices. Knox said, "He advises parents to stop letting their children wear baggy clothes. Many students who are not in gangs are wearing the gangster clothes in expression of youthful rebellion, he said, but there could be danger involved.

"Today's gangster look is a hazard. Why would you let them dress like a target at the pistol range?" Knox said.

Knox said parents need to practice even-handed discipline with their children. Make them follow rules, he added.

His living proof of his words is Garcia, whose friends are following the rules handed down by prison guards instead of their parents. He said of the 25-gang members he used to associate with, all but four are in prison or dead.

"Mike changed my life," he said, "He kept telling me if I didn't stop, I'd end up dead or in prison. I wish there were more guys out there like Mike."