An alleged member of the MS-13 gang pleaded not guilty today for the 2016 murder of a Long Island teen.

Prosecutors say Elmer Gilberto Santos Contreras, an undocumented immigrant from El Salvador, is responsible for the death of 18-year-old Estiven Abrego Gomez in August 2016.

As News 12 previously reported, someone walking at Tri-Village Greenlawn Park and discovered the body and called police. At the time, police say Abrego Gomez had severe lacerations throughout his body, his hands were almost severed and his face was so badly beaten, he was unrecognizable.

Investigators says Contreras and another member alleged MS-13 gang member, Anthony Gutierrez Mesa, acted together in the murder.  Gutierrez Mesa is being held in Virginia for unrelated charges and is waiting to be extradited back to New York to face second-degree murder charges in this case.

Suffolk County District Attorney Tim Sini says Contreras allegedly ordered a hit on Abrego Gomez after the victim was seen on social media flashing gang signs of the 18th Street gang, a known rival to MS-13.

Despite his not guilty plea, investors say Contreras made a written confession.

Contreras was in ICE custody in Virginia for a misdemeanor when Suffolk County detectives brought him to Long Island, but Sini told News 12 they are not sending him back to El Salvador.

"This is a dangerous homicidal sociopath that we are not simply going to let walk out the door, go back to El Salvador and potentially illegally re-enter the United States," Sini said. "So those people who don't understand why we prosecute people who are here illegally, that's why, we have to make sure he's in jail so he can't kill other people."

Contreras is being held without bail. If convicted, he faces a maximum of 25 years to life in prison.