The film, which lasts a brisk 92 minutes, was shot by the same cinematographer, Barry Ackroyd, who brought a real-time feel to films by directors Paul Greengrass and Kathryn Bigelow.

It chronicles the events over three days, from the time Kennedy was shot an hour after his arrival in Dallas, until his killer, Lee Harvey Oswald, shot the following day by Dallas nightclub owner Jack Ruby, was buried.

The film pounces on the odd, poignant or telling details of that fateful weekend, such as the coincidence that Kennedy and his killer died a little more than 24 hours apart in the same hospital, Parkland Memorial.

Secret Service agents are shown removing seats from the presidential plane so that Kennedy's body can be flown back to Washington accompanied by his widow, Jacqueline Bouvier Kennedy, and the new President Lyndon Baines Johnson, in the passenger compartment rather than in the cargo hold.

Landesman said the 26-second-long Zapruder film, which has been pored over for clues to prove and disprove the assertion that Oswald, firing a cheap rifle from an upper floor of the Texas School Book Depository, acted as a lone assassin, was "probably the most examined film in the history of man".

He said that the family had given permission for and licensed its use in "Parkland" where it is shown to eerie effect reflecting off Giamatti's glasses as law enforcement officers view it for clues.

"We've seen it on the screens, on television but what I wanted to do as a filmmaker, as we all want to do as filmmakers, was to present this film as he (Zapruder) would have seen it...for the very first time," Landesman said.

The film also shows Oswald's brother Robert, who worked at a clerical job, and their mentally unhinged mother, who thinks her dead son was a top secret agent, burying Oswald at a grave where there are no pall bearers because none will touch the casket.

"This is where the truth is - you want to find the DNA of why he may have pulled the trigger you look at his mother, you look at the relationship with his brother. This is the emotional fabric of...the kind of honest film I hope we've made," Landesman said.