#Why won’t NYC keep violent suspects behind bars?

Just what exactly do criminals have to do to be kept behind bars in New York? After all, being arrested in connection with a murder — a murder! — wasn’t enough to keep Jordon Benjamin locked up. Not even did being hauled in a second time, for allegedly slashing a woman (while the murder case was still pending, no less), land him in jail.

It’s positively mind-boggling. And it helps explain why hundreds of thousands of New Yorkers have moved out this year.

As The Post reported Tuesday, 16-year-old Benjamin was allegedly part of a group of teens who attacked a 60-year-old man, Juan Fresnada, and his roommate on Christmas Eve last year. A video shows Fresnada being savagely stomped on and beaten with a garbage can. He later died from his injuries, police say.

Benjamin was confined to a Brooklyn juvenile center on a manslaughter charge but let loose by Bronx Judge Denis Boyle in March due to concerns over the coronavirus. Freed to roam the streets, the teen allegedly slashed a young woman, Amya Hicks, in The Bronx this month.

So what did Boyle do? He let him go a second time. Despite Benjamin being charged with felony assault, attempted assault and misdemeanor weapons possession.

“This is crazy,” fumes Hicks’ mom, Tynisha Smith. Her daughter doesn’t have an order of protection against him, and Benjamin “hangs out” just two blocks away. “He can hurt another person.”

Court spokesman Lucian Chalfen insists Boyle followed the law, which requires judges to impose “the least restrictive alternative” when considering bail.

But if so, it only underscores the disaster of Albany’s 2019 bail reform, which made it almost impossible to keep a suspect locked up — or even to require cash bail to be posted prior to release.

Indeed, the “reform” was so rushed and poorly structured, lawmakers themselves felt the need to “fix” it this year, but still couldn’t get it right. They left judges’ hands tied, denying them a chance to consider the risk to public safety when deciding whether to free a suspect. (The changes this year also left threats to the safety of witnesses, whose IDs and other info must be made available to defense attorneys early in the prosecution.)

The more recent charges against Benjamin also highlight the insanity of officials’ decision to release inmates for fear of COVID spreading in jails and prisons. Surely, there must’ve been some way to keep a defendant charged in connection with a killing away from the public without spreading the virus.

Fueling the damage still more was the 2018 Raise the Age law, which upped the age of criminal responsibility in New York to 18, from 16.

Benjamin’s case proves Police Commissioner Dermot Shea right when he blasts the criminal-justice system for its revolving-door approach to dangerous criminals. The commish cites prosecutors and judges in particular for going easy on perps, an attitude that is driving up violent crime in the city: The NYPD is only “one part of the criminal-justice system,” he says. “We’re not the jury. We’re not the prosecutors.”

As of Dec. 20, murders are up 40 percent this year, burglaries 42 percent, auto thefts 68 percent and shootings nearly double. How high must the figures go — how many New Yorkers must be violently attacked — before lawmakers, prosecutors and judges decide enough is enough?