Son Accused in Hedge Fund Founder Death Is 'Damaged,' Ex-Girlfriend Says

— -- Anna Rothschild, an ex-girlfriend of Tommy Gilbert, the 30-year-old man being held without bail in the fatal shooting of his father, told ABC News today that he'd described the two men's relationship as "strained" and "stressful" for him.

"It made me very sad, actually," said Rothschild, who met with Gilbert for dinner about two weeks ago. She said at that time, he seemed "totally fine" and "happier."

Thomas Gilbert, 70, the founder of Wainscott Capital Partners, was found shot dead in his Manhattan apartment Sunday, police said, and Tommy Gilbert was taken into custody around 10:45 p.m. that day.

Rothschild said she met Tommy Gilbert at a mutual friend's birthday dinner in December 2013 and they started dating.

"He was very sweet, very nice, very quiet, very introverted," she said today. "He wasn't working at the time because he was trying to start a hedge fund."

Rothschild, who eventually broke up with him in May after meeting someone new, said Tommy Gilbert told her that he felt like a disappointment to his father.

"His father was never happy with anything he did or nothing was ever good enough," she recalled him saying.

He always picked up the tab when they were dating and that he never complained about money, she said. But because he was not working, she said she assumed his parents were helping him financially.

Authorities said they believed Thomas Gilbert was killed by his son, who then left the murder weapon -- a .40 caliber Glock 22 -- in the bedroom to make it look like a suicide.

They said Tommy Gilbert entered his parents' Beekman Place home Sunday afternoon and asked his mother to get him a sandwich. When she returned to the apartment, she found her husband shot in the head in his bedroom, police said.

Tommy Gilbert was questioned by police and arrested at 11 a.m. Monday, police said.

Thomas Gilbert recently had discussed no longer paying his son's rent as well as reducing his weekly allowance from $400 to $300, investigators said. Tommy Gilbert was in debt and unemployed, they said, also noting that his mother had told them about a history of mental illness.

Rothschild, who never met Tommy Gilbert's parents, said she was "shocked" to hear that he'd been accused of murder. She said she believed he was "damaged" by his father and that he had endured a "lifetime of pain."

"I never could foresee that he would be violent," she said. "He was never even angry. He was always quite even-tempered."

Tommy Gilbert has been charged with murder in the second degree along with a weapons charge and 21 counts of criminal possession of forgery devices. Police said they found 21 blank credit cards as well as a skimming device in his apartment. Tommy Gilbert did not enter a plea during his court appearance on Monday.

A lawyer representing Gilbert declined to comment on the case to ABC News.