The movie is about Batman’s main villain, the Joker, and serves as an origin story.
In a letter sent to the new CEO of Warner Bros., Ann Sarnoff, Sandy and Lonnie Phillips told the media company it has a "responsibility to the public."
The Phillipses lost their daughter, Jessica Ghawi, in the shooting.
A gunman opened fire inside Theater 9 of the Century Aurora 16 movie theater during a midnight showing of the Batman film "The Dark Knight Rises" on July 20, 2012, killing 12 and injuring 70.
"Our concern is the copycats that might be out there,” Sandy Phillips said. "That those who are kinda on the edge and might be thinking about, ‘I want to be the next masked shooter,' that this [film] might trigger them."
On top of that, Phillips said she’s also concerned about the well-being of victims’ family and friends.
“Even more importantly, what it does to those of us who have been in a mass shooting or affected by gun violence in our country,” Phillips said. “And how that triggers PTSD."
In the wake of the shooting, the Phillipses created the nonprofit group Survivors Empowered. The organization’s goal is to "help empower" mass shooting survivors and their families.
According to Sandy Phillips, the letter sent to Warner Bros. should have arrived Tuesday morning.
"We’re not asking them to can the movie. We’re asking them to take responsibility for what that does to other people in our society,” Phillips said.
While the letter does not ask the studio to halt the release of the movie, it does ask Warner Bros. to "end political contributions to candidates who take money from the NRA and vote against gun reform … [and to] use your political clout and leverage in Congress to actively lobby for gun reform. Keeping everyone safe should be a top corporate priority for Warner Brothers.”
Other family members who lost loved ones in the shooting signed the letter also.
One person who did not was Tom Sullivan, whose son Alex was killed in the shooting.
Sullivan, now a Democratic representative from Centennial, said he has no reason to believe the new "Joker" film will inspire anyone to carry out a copycat shooting.
"If it creates a conversation and we think it can help with mental health issues, then it’s probably a good thing,” Sullivan said.
Sullivan added "Joker" is his least favorite villain, but said he’s not going to tell people to boycott the film.
In the letter to Warner Bros., the Phillipses asked the movie studio to use their money for good and to make a donation to either their organization or another group with a similar cause.
“This movie is about violence,” Lonnie Phillips said. "And the money they make on violence should go to the people who it affects”.
Warner Bros. has not responded to an interview request regarding the letter.
As of Tuesday morning, the Phillipses had not heard back from the movie studio.