An alleged jihadist arrested in June on charges that he plotted to blow up Times Square may also be the fiend who stabbed a 9-year-old Staten Island boy in the neck five months earlier in what some investigators now believe was a botched ISIS audition.

But NYPD detectives investigating the Jan. 9 knife attack have been frustrated by the feds, who won’t give them access to terror suspect Fareed Mumuni, said a source familiar with the probe.

Mumuni, 21, lived only 600 yards from Jermaine Culver, who was stabbed as he walked to school in the Mariners Harbor section of Staten Island.

A surveillance camera on a home across the street captured a stocky attacker as he stalked the boy from behind on Union Avenue before grabbing him around the neck and stabbing him in his back, head, neck and arm.

Jermaine is seen stumbling a few steps before he regains his footing and runs.

“It looks like he’s trying to kill that kid,” said Luis Padilla, 44, the home’s owner. “He went straight for the jugular.”

Following the savagery, Jermaine was afraid to leave the hospital. The shell-shocked boy was eventually sent to live with an aunt in Atlanta.

“But he’s alive and fine and well,” said his 21-year-old brother, Shawn Williams.

Williams said the family remains in the dark about his case a year later.

“We still don’t know,” he said. “It seems like the cops gave up on it.”

In the days after the attack, cops distributed fliers reading, “Wanted for Assault 1,” with a surveillance photo of the attacker running down Leyden Avenue. The NYPD also stationed a mobile command unit at the corner of Union and Leyden.

“They came up with less than zero,” the source said.

Cops got their first break in the case when federal agents with the Joint Terrorism Task Force foiled an alleged four-man, New York-New Jersey terror operation in June. The group had been under surveillance since at least April.

Munther Omar Saleh, 20, of Queens, was arrested on June 13 and charged with plotting to use a pressure-cooker bomb to attack Times Square or One World Trade Center. He had also been spotted surveilling the George Washington Bridge.

Mumuni, who was studying social work at the College of Staten Island, and Saleh, a student at Vaughn College of Aeronautics and Technology in Queens, had met multiple times in May, according to court documents.

They were captured on phone recordings and “exchanged electronic communications in which they discussed attacking members of law enforcement,” the papers say.

Four days after Saleh’s arrest, the task force descended on Mumuni’s Mersereau Avenue home at 6:35 a.m. to execute a search warrant.

Mumuni tried to bury a kitchen knife in an agent’s chest, authorities said. The blade was stopped by the agent’s body armor.

Mumuni, court documents say, “espouses violent jihadist beliefs.” He allegedly told authorities that he had pledged allegiance to ISIS and that if he failed to join the group in the Mideast, he planned to attack law enforcement.

Investigators believe that if Mumuni was the man who knifed Jermaine, the attack could have been Mumuni’s audition for the ISIS, the bloodthirsty terror group that has released a series of videos of hostage decapitations.

“If you look at the video, it looks like he was trying to slit his throat,” the source said.

NYPD detectives want to quiz Mumuni in the assault, describing the purported jihadist as a “person of interest.”

He has a physical “similarity to the description in the video, he lived three blocks away, and he likes to play with knives and attempted to stab a federal agent,” the source said.

Detective Edward Patterson of the 121st Precinct on Staten Island is assigned to case.

Mumuni’s attorney, Anthony Ricco, could not be reached for comment.

Additional reporting by Michael Oates