2:19 PM PT -- Mike Senecal -- the father of Katherine Senecal, who was a victim of the 2012 shooting and helped save her friend who was shot -- tells TMZ ... his daughter would not have echoed the sentiments of the letter sent to Warner Bros.
He says Katie would have been able to separate the movie from real life, and Mike believes those who can't are part of the problem. He adds that violent people exist regardless of whether "Joker" comes out, and people who have issues with the film don't have to see it.
Mike says he plans to see the movie and thinks his daughter would have too. Sadly, Katie died last year by suicide. He says she struggled with mental health issues before the shooting, and she recognized the biggest epidemic in this country is a lack of mental health care ... not movies.
1:06 PM PT -- Warner Bros. has responded to the letter, saying it recognizes gun violence is a critical issue and is taking steps to "address this epidemic."
The company adds ... "At the same time, Warner Bros. believes that one of the functions of storytelling it to provoke difficult conversations around complex issues." WB says "Joker" is not an endorsement of real-world violence ... and the character is not meant to be a hero.
Joaquin Phoenix's performance as the Joker in Todd Phillips' dark take on the Batman villain is getting huge buzz, but at least one theater in Aurora, Colorado won't be showing the film ... the venue where the 2012 mass shooting occurred.
The Century Aurora and XD is the remodeled site where James Holmes -- armed with an assault rifle and other guns and wearing full body armor -- attacked moviegoers at a screening of "The Dark Knight Rises," killing 12 and injuring 70.
Holmes became linked to the Joker because of his bright orange hair and reports he called himself that when he was arrested ... though those reports turned out to be false.
The theater reportedly will not be showing "Joker" -- there are currently no showtimes listed and a theater employee tells The Hollywood Reporter no advance ticket purchases are available because the multiplex won't be showing the film.
It's unclear if this is out of respect, or fear of a copycat incident.
Either way, the decision to pass on "Joker" comes as family members of the Aurora shooting victims are expressing concerns about Phoenix's portrayal of Arthur Fleck, who becomes the Joker, and the violence that laces the film ... asking Warner Bros. to join the corporate leaders who understand "they have a social responsibility to keep us all safe."
Sandy Phillips -- mother of Jessica Ghawi, who was one of the 12 killed -- and her husband, Lonnie, along with 3 other family members of victims, all signed a letter sent to Warner Bros. voicing fears over the movie and asking the studio to donate to groups that help victims of gun violence.
Sandy says the movie feels "like a slap in the face" and she's terrified ..."My worry is that one person who may be out there -- and who knows if it is just one -- who is on the edge, who is wanting to be a mass shooter, may be encouraged by this movie."
She adds ... "For me, it's the gratuitous violence that this film glorifies and elevates with the Joker character."
The letter to Warner Bros. states that the 2012 shooting was "perpetrated by a socially isolated individual who felt 'wronged' by society" and acted on it.
The letter asks the studio to end political contributions to candidates who support the NRA and encourage Congress to lobby for gun reform, but it does not ask for the "Joker" release to be halted or canceled, nor does it call for a boycott.
It's a little weird ... the letter more than suggests releasing the movie is irresponsible and dangerous, but then it goes on to say they support free speech -- even if it's harmful.
Warner Bros. says it has not yet received the letter. We've reached out ... no word back so far.
We got Marc Maron at LAX Monday, and he actually touched on the topic too. He tells us he doesn't buy the notion that movies like "Joker" inspire real-world violence ... because it's a more deep-seated issue with mental illness.
Marc also has a small role in the film and says he's excited to see it at the upcoming premiere. He also gives us an idea of what Phoenix went through to get into character.
Fans of the movie got a first look at Phoenix as both Fleck and the Joker about a year ago, and in both instances ... he looks pretty creepy.