"A lot of people have asked me, 'Why don't we see Chris get killed?'" Hall told PEOPLE while promoting the film last month. "It's a fair question, but this was about Chris's life, and it was also a movie that involves his kids."
Still, he and the film's other collaborators – including director Clint Eastwood and star Bradley Cooper – did consider including Chris's murder in the final cut, Hall told the New York Daily News. "We talked about putting it in," Hall said. "I certainly wrote it. We went around and around and I wrote it five different ways and talked about how we would shoot it."
Recalling a conversation Hall had with Chris's widow Taya a few days after Kyle's funeral, he says she told him, "If you guys are going to do this, you're going to need to get it right. This is going to play a part, for better or worse, in how my kids remember their dad."
Hall met Chris, known as the most lethal sniper in U.S. history, when he was working on bringing the Navy SEAL's 2012 bestselling autobiography to the big screen. On Feb. 2, 2013, the day after Hall handed in the first draft of the screenplay, Chris was fatally shot on a Texas gun range at age 38 while trying to help Eddie Ray Routh, a fellow veteran who was allegedly suffering from PTSD.
Ultimately, Eastwood had the final word on the film's ending, says Hall. But being a father of two himself made Hall think about how the death scene would affect Chris's children when he penned the final script.
"For me, I didn't want this movie hanging over [Taya's] kids' heads for the rest of their lives," he told PEOPLE.
"And I didn’t want to glorify [Routh]," he added.
The film ends with Taya (Sienna Miller) looking anxious as she peers out the front door of their home while Chris (Cooper) heads to the Rough Creek Lodge with Routh.
"The way in which it was done onscreen – Clint does it is so brilliantly that you don’t even realize it's happening," says Hall. "There are two points of view in the movie: Taya's and Chris's. For her, this is how it happened, in a moment where it was just another day and then he was gone."
In an earlier interview with PEOPLE, Taya shared her thoughts on the film's final scene.
"The look and the caution that you see in Sienna's face is a constant," said Taya. "It's like, 'You're going to do this and I hope this guy is okay.'"