Members of an El Salvadorian street gang stabbed a man 100 times, beheaded him and cut out his heart in a park near Washington DC, police say.
Up to 10 members of MS-13 communicated on walkie talkies as they closed in on their victim at a recreational area in Wheaton, Maryland, say officials.
The victim's "heart had been excised from his chest and thrown into the grave", according to court records.
US President Donald Trump has vowed to wipe out MS-13.
One of the suspects, 19-year-old Miguel Angel Lopez-Abrego, appeared in court on Wednesday, according to Montgomery Community Media.
He has been charged with first-degree murder and remanded in custody.
He was arrested in North Carolina on 11 November and extradited to Montgomery County, Maryland.
According to the Washington Post, the victim was murdered in early spring, but police only became aware of the killing after a tip-off.
The body was discovered in Wheaton Regional Park on 5 September.
The victim had been buried in a woodland grave prepared before his murder, officials said.
Investigators are still trying to identify the victim, but he is thought to be a Hispanic male.
A post-mortem examination ruled it a homicide from "sharp force injuries", said police.