Six members of the MS-13 street gang have been indicted in connection with three slayings, federal prosecutors said Saturday.

Two killings took place on Long Island and the other in Queens, prosecutors said. The two Long Island slayings were in the Brentwood-Central Islip area and were part of a series of violence that prompted Suffolk police earlier this year to increase staffing levels and visibility in the area.

Prosecutors say that one victim was killed because members mistakenly thought he was in a rival gang, another because he was a rival gang member and the third because he was an MS-13 member who didn't have enough "heart" to kill members of rival gangs.

The victim mistaken for a rival gang member was Dexter Acheampong, 24, who was shot to death in Central Islip in May 2009. The MS-13 members accused in his death assumed Acheampong was with the Bloods, according to court records and sources.

David Sandler, 20, of Brentwood, was fatally shot in February. He had been associated with the Latin Kings, according to sources and records.

The MS-13 slain member was Mario Canton Quijada, 25, of Far Rockaway. Prosecutors said he was hacked and stabbed to death with a machete and knives on a Far Rockaway beach in March.

Charged in the conspiracy to kill Quijada were MS-13 members Jeremias Amaya, Roger Alvarado and Carlos Martinez. Charged in the Sandler death were Mario Herrara-Umanzor, David Sosa and Alvarado. Jose Orellana-Torres was charged in the Acheampong slaying. Officials did not release their ages or addresses.

All six were indicted in federal court in Central Islip Friday.

Amaya, Sosa and Orellana-Torres pleaded not guilty and were held without bail. The others are scheduled to be arraigned later.

Alvarado's attorney, Kenneth Keating, said Saturday, "We are troubled by the new allegations, and will be looking into them and we will continue to fight."

The indictment supersedes the charges brought against more than a dozen members of the gang in April. The indictments were the result of a joint investigation into Long Island gangs by the FBI and the Nassau and Suffolk police forces, officials said.

Amaya's attorney, Richard Lind, declined to comment Saturday, as did Assistant United States Attorney John Durham. Attorneys for the others indicted did not immediately return calls.

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