Four gang members have pleaded guilty in the 2014 fatal shooting on Long Island of a fellow member they suspected of snitching on them, authorities said Thursday.

Milton Contreras, 20, and Jose Osmin Rubio, 25, both of Brentwood, pleaded guilty Thursday to murder using a firearm, while Byron Lopez, 25, of Queens, and Oscar Welman Espinoza-Merino, 23, of Brentwood, pleaded to the same charge last month, according to the U.S. Attorney’s Office for the Eastern District, which covers Long Island.

The defendants, part of the MS-13 street gang, face life imprisonment for luring Sidney Valverde, 19, to Long Island on Feb. 25 under the pretense they needed his help on gang business, then shooting him in the back of the head, authorities said.

The victim’s body was dumped on Miller Place Beach, where a beachcomber discovered it about two weeks later.

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The gang members suspected Valverde of giving law enforcement information about MS-13 activities.

Authorities have been cracking down on the gang, also known as La Mara Salvatrucha, which prosecutors describe as a “violent international criminal organization.”

Since 2003, hundreds of MS-13 members have been convicted on federal felony charges ranging from murder to racketeering in the Eastern District, which also covers Queens, Brooklyn and Staten Island, federal officials said.