Steve Carell plays an heir to the DuPont Chemical fortune, John Eleuthere du Pont, in the movie “Foxcatcher.”

The movie is based on the true story of du Pont’s association with amateur wrestling in the 1980s and 90s, specifically the Olympic champion brothers Dave and Mark Schultz. Du Pont sponsored the Schultz brothers, who had won gold medals in 1984, and the rest of the US wrestling team on his Foxcatcher Farms estate, giving them a state-of-the-art facility, room, board, and salaries.

Until he murdered Dave Schultz.

Schultz’s widow, Nancy, his brother Mark, and several wrestlers who stayed on the du Pont estate were involved in filming of “Foxcatcher.” The first time Carell met Nancy Schultz, he was made up to look like the man who had murdered her husband.

“I didn’t meet her as myself. I met her in character, which was doubly awkward, because they tried to make me look as much like du Pont as I could,” Carell said in a press conference after the movie’s premiere at the Cannes Film Festival. “It was incredibly emotional obviously, and she’s a remarkable woman … very, very, giving, and very understanding of what we were trying to do, and the dignity that we were trying to afford her.”

Mark Schultz also spent some time on set, which was somewhat unsettling to the actor playing him, Channing Tatum.

“He definitely coached me early in the movie, wrestling wise, and when he was on set … at times I was so thankful and grateful that he was there, and at other times I was completely terrified,” Tatum said. “When you are literally looking off camera and the person you are playing is there…”

“I think it was as hard on [Mark], too, as it was on all of us,” added Mark Ruffalo, who plays Steve. “You know, you go through a bad time in your life once, and then you have to go through it again on a movie set, it’s a little heavy.”

Director Bennett Miller (“Capote,” “Moneyball”) said the tragic tale was one he had a hard time getting his head around.

“When I started learning about the story, and learned the details of it, it was so bizarre, I had never personally encountered anything that resembled any of this behavior,” Miller said. “And what happened was so bizarre and absurdist, and sometimes comical, and ultimately horrible.”

Tatum said he and Ruffalo went full-bore into learning how to wrestle to prepare for their roles.

“We wrestled for about 5 to 6 months before, and Mark and I both have cauliflower ear as take-home presents from it,” he said.

“Bennett asked us to really immerse ourselves in that world, so our life became wrestling, eating, sleeping, and finding out who these people were,” Ruffalo added.

Recreating the vast Foxcatcher Farms estate outside Philadelphia was another issue.

“We did get lucky that family, and I’m not permitted to say which, a du Pont type family in terms of their history and wealth, invited us onto their 17,000-acre estate and horse ranch, which had an amazing resemblance to Foxcatcher Farms,” Bennett said. “They had never permitted any outsiders to even photograph it before. I met with them, I sat around the table with characters that could have been in the movie, and told them what we were trying to do and asked for their support. It was the most inexpensive location on the movie, and one that money could not have bought.”

And the du Ponts?

“We had a little bit of contact with some members of the family before shooting,” Bennett said. “But no contact since.”