Robert F. Kennedy Jr., the nephew of the former President John F. Kennedy, is speaking out this week to say that he believes there was more than one gunman responsible for his uncle’s assassination in 1963. He also said that his father, the late Robert F. Kennedy, believed the Warren Commission report was a “shoddy piece of craftsmanship.”

After JFK’s assassination on November 22, 1963, the Warren Commission concluded Lee Harvey Oswald acted alone in killing the president. RFK Jr., however, said that both he and his father, who was assassinated himself in 1968, were not buying that.

“The evidence at this point I think is very, very convincing that it was not a lone gunman,” he told NBC News, not elaborating further on what he believes happened.

RFK Jr. was then asked if his father, who was U.S. attorney general at the time of the then-president’s assassination, felt “some sense of guilt because he thought there might have been a link between his very aggressive efforts against organized crime.”

“I think that’s true. He talked about that,” he replied. “He publicly supported the Warren Commission report but privately he was dismissive of it.”

RFK Jr. went on to say that investigators hired by his father to do research into the assassination found that phone records of Oswald and nightclub owner Jack Ruby, who killed Oswald two days after the president’s assassination, “were like an inventory” of mafia leaders being investigated by the U.S. government at the time. This led RFK to become “fairly convinced” that others were involved in his brother’s death.

RFK Jr.’s sister Rory, a documentary filmmaker who sat with him for this interview, tried to focus on happier memories. She said that despite the tragedy that her family faced, they grew up in a culture that stressed the importance of giving back.

“In all of the tragedy and challenge, when you try to make sense of it and understand it, it’s very difficult to fully make sense of it,” she said. “But I do feel that in everything that I’ve experienced that has been difficult and that has been hard and that has been loss, that I’ve gained something in it.”

RFK Jr. agreed with his sister, saying, “We were kind of lucky because we lost our members of our family when they were involved in a great endeavor. And that endeavor is to make this country live up to her ideals.”

Conspiracy theorists have long believed that there was some kind of coverup in the assassination of JFK. This latest interview will certainly add fuel to that fire moving forward.