A maniac ex-cop was arrested Saturday in the brutal murder of a young woman jogging along a Brooklyn footpath last week — and he claimed he woke up covered in blood with no memory of the heartless stabbing, police sources told The Post.

Sayed Mohassib, 27 — who currently works as an elementary school educator in Brooklyn despite being discharged from the Marines for psychological reasons — was charged with second-degree murder in the Oct. 30 slaying of Katie Suarez , police sources said.

Officers tracked him down to his Bensonhurst, Brooklyn, home after picking him up on video leaving the Shore Parkway Greenway around the time Suarez was attacked, the sources said.

Mohassib told cops during his grilling at the 62nd Precinct stationhouse Saturday that he woke up from a blackout covered in blood and with the murder weapon.

He said he ditched the knife in the garbage, and cops believe the trash was taken to a Staten Island landfill before ending up at a New Jersey dump.

The accused killer is a paraprofessional at PS 200 — which is just three blocks from the waterfront promenade overlooking Gravesend Bay — and returned to the school to work with children just days after allegedly carrying out the savage murder.

Colleagues there noticed him speaking incoherently and acting erratically, according to sources. They reported the concerning behavior to police, though their reports weren’t what ultimately led to his arrest, the sources said.

Students also were concerned by Mohassib’s demeanor.

“He was acting a little bit weird. A bit off,” a 12-year-old boy playing near PS 200 told The Post.

The boy and a friend said they saw the educator talking to himself, with the other child describing his behavior as: “nervous, worried.”

Students gathered outside the 62nd Precinct, across the street from the Bath Beach school, to watch as Mohassib was escorted out of the station at 4 p.m. Saturday.

A handcuffed Mohassid, wearing a bright red Von Dutch jacket, appeared dazed and eerily calm as he walked to the cop car.

He showed no emotion as someone shouted, “F–k you!” from across the street.

Mohassib has a history of mental instability — with his own family calling 911 after he threatened to “chop them up,” according to sources.

His mother and sister reported the incident to cops in September 2024, and officers found him at Caesar’s Bay– about a half-mile from where Suarez was killed, the sources said. He was taken to Coney Island Hospital in that incident.