NEWARK — Federal prosecutors on Wednesday announced the dismantling of a Newark-based drug gang, which they say used social media to scare off rivals and plotted to kill an undercover FBI agent.

Fifty members of the Grape Street Crips have been charged in 14 separate criminal complaints that accuse them of controlling the sale of cocaine, crack cocaine and heroin in public housing projects located blocks away from the federal courthouse as well as neighborhoods throughout Newark.

Another 21 have already been arrested and are facing state and federal drug-trafficking charges.

The gang is an offshoot of the Los Angeles-based Crips criminal gang, prosecutors say.

"As this investigation demonstrates, the New Jersey Grape Street Crips are allegedly one of the largest and most dangerous street gangs in Newark as well as a prolific narcotics trafficking organization that floods the streets of New Jersey with heroin, cocaine and crack cocaine," New Jersey U.S. Attorney Paul Fishman said at a press conference in his Newark offices Wednesday.

Fishman said the gang used the initials "K.A.R." — shorthand for "Kill All Rivals" -- on various social media postings in an effort to scare off would-be challengers.

And, prosecutors say, Corey Batts, 30, one of the gang's alleged leaders, plotted to kill an undercover FBI agent by passing along an image of the agent to a fellow gang member while he was locked up.

Batts obtained the agent's image — taken from a surveillance photo -- through pretrial discovery after his arrest last summer, prosecutors say.

Batts remains in jail and has been charged with attempted murder and conspiracy to commit murder.

Two months ago, alleged gang member Ahmed Singleton, 25, managed to get aggravated assault charges pending against him dismissed after he stationed "goons" in a Newark courtroom to intimidate a witness, prosecutors say.

The witness' lawyer informed Singleton that his client would "do the right thing" and not testify against him to avoid being harmed, they added.

Singleton was later recorded on a cellphone bragging about what he'd done, prosecutors say.

"I walked out of court free, who you know do that?," Singleton bragged in March 2015, according to prosecutors. "Who you know cause ruckus on these (expletive) streets, come home, do whatever the (expletive) they want, and still be out here son?"

Singleton was arrested on a charge of conspiring to distribute heroin on May 5 and is being held at the Essex County Jail.

Acting Essex County Prosecutor Carolyn Murray said the incident highlighted the challenges state prosecutors face in making cases when witnesses fear for their safety.

"This case before us really puts in some perspective and provides additional detail about a problem that we have in

Essex County

which is witness intimidation and attempts to obstruct the administration of justice," Murray noted.

Fishman said the gang used violence and intimidation to maintain a stranglehold on the drug trade in certain sections of the city where demand appeared to be insatiable.

He said a single cell phone that gang members used to field drug requests logged more than 110,000 calls — 180 per day — between May 2013 and January 2015.

"That's right, one cell phone," Fishman said. "This was a community cellphone, which was passed along and shared by members of the gang. It was effectively a virtual switchboard."

So-called "community guns" were also shared among gang members operating in the area of 6th Avenue and North 5th Street, prosecutors say. Among the weapons seized were a .410-caliber assault rifle, numerous semi-automatic handguns and a .45-caliber Thompson semi-automatic carbine.

Newark Police Chief Anthony Campos said many gang members failed to get the message despite warnings from officers that if the drug dealing continued, a concerted push by state and federal law enforcement authorities was on the way. "We told the bad guys, we warned them 'if you continue to do this we're going to bring the full weight of the criminal justice system down upon you'," Campos said. "Well I guess they chose not to listen."

The long-running investigation called on the work of agents from the Drug Enforcement Administration, the FBI, the Newark Police Department and the Essex County Sheriff's Office, among others.

"Gangs are the mechanism by which drugs are transmitted to the 'bad seeds' in our cities and are at the root of the violent crime problem," said Bradley Cohen, the FBI's assistant Special Agent in Charge of the Newark field office.

Thomas Zambito may be reached at tzambito@njadvancemedia.com. Follow him on Twitter @TomZambito. Find NJ.com on Facebook.