The son of a hedge fund founder was charged Monday with killing his father after the two argued over allowance money, authorities said.

Thomas Gilbert Jr., 30, was charged with several offenses, including second-degree murder and multiple counts of criminal possession of a weapon after he allegedly shot his father, 70-year-old Thomas Gilbert Sr., in the head Sunday afternoon, police said. The two had previously argued about money -- Gilbert Sr., who founded Wainscott Capital Management in 2011, wanted to cut his son's weekly allowance, said a law enforcement official with knowledge of the investigation.

Gilbert was held without bail Monday evening, said a spokeswoman for the Manhattan district attorney's office.

Gilbert Jr., who had been arrested in Southampton for an unrelated incident in September, apparently came by the luxury Beekman Place apartment at about 3 p.m. on Sunday and asked his mother if he could speak with Gilbert Sr. alone, Chief of Detectives Robert Boyce said during an unrelated news conference at police headquarters Monday. The mother obliged and left to get some food for her son.

"About 15 minutes after that, she had a bad feeling and decided to return," Boyce said. "She got back to the apartment about 15 minutes later and she found [Gilbert Sr.] on the floor with a bullet hole in his head."

Gilbert Sr.'s body was lying in the bedroom, between the bed and the wall, with a gun on his chest, underneath his left hand, according to police and the criminal complaint. There was an additional round left in the gun. His wife called 911 at about 3:30 p.m.

The crime, however, appeared too staged to be a suicide, Boyce said. Additionally, more than 20 blank credit cards were recovered from the apartment, according to the criminal complaint.

On Sunday evening, police searched Gilbert Jr.'s Chelsea apartment on West 18th Street and found several items, including two .40 caliber magazine clips, numerous loose rounds and a shell casing envelope with the serial number of the gun that was found at the crime scene, Boyce said.

By Monday afternoon, neighbors remembered the Princeton and Harvard educated Gilbert Sr. as a kind and courteous man.

"He was always extremely nice to me and my dog," neighbor Pierre Gazarian said, who has a sheltie named Nina. "He'd always lean over, pet her. What I remember most is his smile and how he treated my dog.

"There was a civility about him," Gazarian, 75, added. "It makes the whole thing even more miserable."

Emilio Quintero, 43, said Gilbert Jr. would visit the nearby Nations Cafe once or twice per week for an early breakfast, often after running.

"Pancakes, coffee and juice. His favorite was blueberry pancakes," said Quintero, who has worked there for years. "He always came with the newspaper. He was nice."

Quintero said he would either come in his suit or running clothes, but he would always request the table by the front window. He would come between 6:30 and 7 a.m.

"I was really shocked," Quintero said. "He never talked about his family."

This was not Gilbert Jr.'s first arrest. On Sept. 18 he was arrested by Southampton Town Police for violating an order of protection weeks earlier, according to a criminal complaint.

Gilbert Jr. approached Peter N. Smith about 7:30 p.m. on Sept. 1 at a nearby beach and "attempt[ed] to engage in discussion" with him in violation of an order of protection issued in Brooklyn on June 18, the complaint said. The Brooklyn case is sealed and no further details could be provided, said a spokesman for the Suffolk District Attorney's office.

A Southampton Town judge issued a second protection order against Gilbert on Dec. 8. and he is due back in court in Southampton on Feb. 22.

Around his Chelsea neighborhood Gilbert Jr. was known as very quiet.

"He used to come every day with his computer, he was in the corner," said the cafe owner, who asked not to be identified. "Here we are always so friendly, say 'hi, how are you.' But he never spoke with no one.

"He would stay all day, all afternoon, all night," the owner added.

(With Karina E. Cuevas and Emily Ngo)