NEW YORK >> he son of a hedge fund founder has been arraigned on second-degree murder in the killing of his 70-year-old father after the two argued over allowance.

Thomas Gilbert Jr. also was charged with criminal possession of a weapon and criminal possession of forgery devices Monday night.

Thomas Gilbert Sr. was shot in the head in his Manhattan apartment after the two argued over the son’s allowance, police said.

The 30-year-old son went to his parents’ home on Manhattan’s East Side on Sunday and asked his mother to go out to get him some food, according to police. About 15 minutes later, she got a “bad feeling” and went back, said Robert Boyce, the NYPD’s chief of detectives.

“She found Senior on the floor with a bullet hole in the head,” Boyce said. “She also found a gun resting on his chest with his left hand covering it.”

But Boyce said it was a staged suicide — his son was trying to cover up the killing.

Gilbert Jr. was in debt and had argued with his father over his allowance, police said.

The attorney for the younger Gilbert didn’t immediately return a call for comment. His next court appearance was set for Friday.

According to the criminal complaint, Gilbert Sr. was found dead lying on the floor near the window of a bedroom. A .40-caliber Glock firearm was loaded with an additional live round, it said.

Authorities found more ammunition at the defendant’s apartment, including two magazines loaded with a total of 17 rounds, loose bullets and empty shell casings, the complaint said. A skimmer device and 21 blank credit cards also were found.

In 2011, Gilbert Sr., a graduate of Princeton University and Harvard Business School, founded Wainscott Capital Partners Fund, which has $200 million in assets.

Gilbert Jr. also attended Princeton, graduating in 2009 with a degree in economics. Authorities said he had no recent work history.

Gilbert Sr. worked on Wall Street for more than 40 years, according to his profile on Wainscott’s website, and he previously co-founded Syzygy Therapeutics, a biotech asset acquisition fund. He also was founder and CEO of an online teacher education company called Knowledge Delivery Systems Inc.

Wainscott, which invests in biotechnology and health care stocks, had no comment.

The shooting was a rare act of violence in the Sutton Place neighborhood, a wealthy enclave just north of the United Nations.

Neighbor Pierre Gazarian remembered Gilbert as “incredibly courteous, elegant,” and praised his “civility (and) caring.”

Gilbert Jr. has a pending criminal case in the town of Southampton, on eastern Long Island.

Gilbert Jr., who has an address in the hamlet of Wainscott, was arrested Sept. 18 on a charge of criminal contempt. Southampton town police say he violated an order of protection issued in Brooklyn in June. Police say he confronted a man named Peter N. Smith at Sagg Main Beach in Sagaponack on Sept. 1.

He has pleaded not guilty and has a Feb. 2 court date scheduled.