EAST MEADOW, Long Island (WABC) -- A 21-year-old man is under arrest in the killing of a teenager whose body was found in a wooded area on Long Island Wednesday afternoon.Authorities say Carlos Benitez-Hernandez is no stranger to the prison system, and this is not the first time he's accused in a barbaric crime. He had been in federal custody on an immigration issue, and now, he's charged with murder.During the dig in East Meadow, which was prompted by credible tips, police recovered the human remains of 21-year-old Carlos Rivas-Majano off Glenn Curtiss Boulevard near the Uniondale border and Kellenberg Memorial High School. They believe the victim was hacked to death one year ago in a case of MS-13 violence.Hernandez is a self-proclaimed member of the notorious gang.Wednesday's discovery was part of a joint investigation with DEA and Homeland Security."It's more the gang's displeasure with his action, within the group or something like that," Nassau County police Detective Lieutenant Stephen Fitzpatrick said. "They felt there was disrespect to them or a threat to them."Police tell Eyewitness News there have now been 10 MS-13 victims slaughtered in Nassau County since 2016, from at least five different factions of the gang, and reputed member of the gang pleaded guilty for his role in the murders of four young men in 2017 last week.Police say the way these killings occur in the woods are all eerily similar."That person has been almost lowered into false sense of security, going in to smoke marijuana, hang out, have a little meeting," Fitzpatrick said. "They just don't know that in that particular case they're marked for death."Authorities believe there are at least four other people involved the murder, and they hope to make more arrests soon."Most of these types of murders by MS-13 are done by at least that many, if not more," Fitzpatrick said. "We believe there's actually more than five in this incident."----------