More than 2,000 alleged gang members have been arrested across New York City in the last 18 months. Police say the takedowns have helped to drive the number of murders to historic lows. But there are questions whether police and prosecutors are unfairly sweeping up low-level offenders in the process. NY1 criminal justice reporter Dean Meminger has more in Part Two of his series on the city's gang crackdown. 

Going after violent street gangs, as if they were the mafia by using federal racketeering and conspiracy charges. Acting U.S. Attorney Joon Kim defends the tactic.

"They do have individuals who are high-up and people who are lower down. There are folks who commit crimes at the direction of senior gang members. And so the idea that those organizations, those gangs are at not organizes is just not factually correct," Kim said.

• NYPD credits reduction in NYC murders to gang takedowns

The number of arrests has been surging - 2,200 alleged gang members taken into custody in the past 18 months.

And with arrests rising, prosecutors are increasingly using the federal Racketeer Influenced and Corrupt Organizations Act, or RICO. It permits prosecution of gang members for being part of an enterprise that commits a series of crimes.

CUNY Law school professor Babe Howell says these RICO cases are too far reaching.

"The central players, the actual shooter, the actual drug seller, we don't need conspiracy, we don't need RICO. There's long sentences associated with those offenses," Howell said.

The problem, Howell says, is that with a RICO charge bottom players in a gang can be tied to serious crimes - even murder - committed by other gang members. Advocates and activists say hitting everyone with a murder conspiracy makes it appear as if all of them are among the worst criminals in the city. Professor Howell says conspiracy charges can even be brought against people who have already been convicted and served time for a past crime.

"A conspiracy charge is not barred by double jeopardy. So, if I sold drugs 5 years ago when I was 16, I was arrested I took a plea. I got a sentence or probation I am now in college. They can swoop back and charge that as part of a conspiracy," Howell said.

Taylonn Murphy's daughter Chicken Murphy who was a standout basketball player was shot dead six years ago in a Harlem gang war. His son Taylonn Jr. was arrested in 2014 in a bust of more than 100 gang members. Murphy is an outspoken critic of the large gang takedowns.

"My daughter was killed due to an altercation bewtween two housing developments and I think it is very unfair that you have these kids indicted on conspiracy to commit murder when it was two misguided individuals that actualy committed the act. It was not the whole Manhattan Avenue that committed the act," Murphy added.

NYPD Chief of Crime Control Strategies Dermot Shea doesn't see it that way.

"The misconception that you hear is that people were swept up in this gang takedowns, could not be further from the truth. Intelligence driven, data driven, working with our partners, we know exactly who is going to be arrested. We know exactly what charges they are going to be charged with," Shea said.

The advocates also complain about a common tactic, saying it’s unfair for law enforcement to target low-level offenders to get them to turn against gang members responsible for the real violence. 

Acting U.S. Attorney Joon Kim has this brutaly honest advice for gangs.  

"Those who you think are your brothers in your gangs when they are confronted with criminal charges many times they will flip and cooperate and tell the truth about what you did. And you don't want to be on the other side of that type of prosecution or relationship either," Kim said.