If the tragic death of a teenage girl, allegedly at the hands of satanic gang members, has taught us anything this week...it’s that parents really need to know who their kids are hanging out with.

KHOU 11 News got expert insight into how these violent gangs lure their victims.

"They kill for a living," said Supervisory Special Agent Mark Sabol, FBI Violent Gangs Task Force. "I work with a lot of seasoned investigators and we all have the same reaction when we see a 14-year-old child that's been decapitated and limbs removed so violently."

The task force tracks everything from the crimes gang members commit to how they recruit.

"MS13 is not taking random girls off the streets, snatching them and doing the kind of things that have been reported lately," said Sabol.

He says girls who fall victim are often knowingly hanging around the gang members. Killing is required for initiation.

The violence stems from El Salvador where the gang started. Last year, the country of 6 million people saw 6,000 murders.

"With this particular gang, there's no way out," said Sabol.

Back home in Houston, FBI agents even see murders caught on video. A gut wrenching reminder that warning signs are something you can't ignore.

"My advice to parents is to educate yourself on gangs," said Sabol.

The FBI created a list of warning signs and what to do if you think your child might be involved. Click here for more information.