NEW YORK (AP) — It’s a role that moviegoers might not know Robert De Niro plays: overseeing his painter father’s estate.

The Academy Award-winning actor served as a star witness Friday in an art-fraud trial, testifying against a former gallery director accused of selling some of the late Robert De Niro Sr’s works without paying his family its share.

Seeming as self-assured on the witness stand as his characters are on screen, De Niro told jurors about his family’s dealings with the now-shuttered Salander-O’Reilly Galleries LLC, giving detailed answers and drawing laughs at times from a courtroom packed with reporters and onlookers.

Larry Salander pleaded guilty last year to bilking about $120 million from De Niro Sr’s estate, John McEnroe and other clients. On trial is Salander’s former gallery director, Leigh Morse.

De Niro told a story of coming to doubt an art dealer he’d trusted and considered a friend.

“I wasn’t watching as carefully as I probably should have” early in the estate’s involvement with gallery owner Lawrence Salander, De Niro said. But “I trusted Larry implicitly. I thought that anything that he did, it was going to be good.”

The 54-year-old Morse is accused of participating in Salander’s scheme and pocketing $77,000 in proceeds from selling two of the actor’s father’s paintings. She has pleaded not guilty to grand larceny and other charges.

De Niro Sr, an abstract expressionist who had “become a little cynical” about art dealers over the years, selected Salander to represent his works, and “I could see why he liked him,” the actor said. After his father’s 1993 death, the actor continued to entrust the estate’s works to Salander, having some dealings with Morse as well.

Sale proceeds and most expenses in getting the artworks sold were to be split 50-50, according to an agreement shown in court.

The gallery arranged shows for De Niro Sr.’s work in several European cities and in Tokyo, and the actor said he attended some and “felt it was going well” at first. But over time, he started wondering about how Salander was financing private plane rides and other expensive plums.

“It didn’t seem to add up to me, but I was under the impression that there were big deals going on in Europe and so forth, and he was making a lot of money in art,” said De Niro, dressed for court in a gray-green velvet blazer and crisp white shirt.

But after a contemporary of his father’s said he felt he was being cheated by Salander, De Niro began asking questions — “gingerly,” he said. Then he discovered that Salander had signed over ownership of some of his father’s work to a gallery in Venice, Italy, without his permission, a move prosecutors say Salander made in 2006 to satisfy his own heavy debt to the gallery.

When asked about relinquishing the paintings, “He said, ‘Oh, that’s nonsense,’ da-da-da, da-da-da,” the actor said. “I felt he was either delusional — deluding himself — or not being honest, and I just didn’t have time for it.”

After cutting ties with the gallery in late 2007 or so, he learned the estate hadn’t been paid its portion of any sales after 2001, he said.

Morse and another gallery employee tried to woo the estate’s business back, but “I wanted to make a clean break from all the bad stuff,” the actor said.

Easygoing and forthcoming with his testimony — to the point of being asked at times to wait for a question to end before replying — the “Raging Bull” and “Analyze This” actor gave the court a wry glimpse of his often flinty characters when one of Morse’s lawyers asked a somewhat convoluted and hypothetical question about his opinion of a certain financial practice of the gallery.

“I don’t know where you’re going, sir,” De Niro said to a laugh from the courtroom audience.

Morse’s lawyers say the crimes were Salander’s, not hers. The top charge against Morse carries the possibility of up to seven years in prison if she is convicted.

Salander, 61, is serving six to 18 years in prison.