Postponed by U.S. violence, Gangster Squad opening in theaters LOS ANGELES (Reuters) - After having its release delayed and scenes reshot because of last summer's mass movie-theater killing in Aurora, Colorado, crime drama "Gangster Squad" finally hits theaters on Friday. "Gangster," set in 1949 Los Angeles, stars Sean Penn as real-life gangster Mickey Cohen, who is ultimately brought down by a band of cops led by Josh Brolin and Ryan Gosling. After the Colorado tragedy, Time Warner Inc's Warner Bros. studio, which is releasing the film, removed the scene in "Gangster" that eerily depicted a similar movie-theater shooting. It substituted a new sequence, set in Chinatown. At a press event in December, "Gangster Squad" director Ruben Fleischer said, "We should all respect the tragedy and not draw associations to our film." But ironically, after "Gangster's" initial September 7 release date was pushed back four months - presumably to allow for time after the Colorado rampage - the film will now open less than a month after the massacre of 20 children and six adults by a gunman at an elementary school in Newtown, Connecticut. Brolin also cautioned at the December event against linking "Gangster" and other movies with real-world violence and suggested the public look at the "grand scheme of things" including social problems such as drug abuse and unenmployment. "There's no one reason" for mass attacks, Brolin told reporters. There will always be violence in movies. And whether it lends (itself) to the one psychotic that's out there thinking the worst thoughts you can possibly think is always going to be a mystery. Details of the Aurora multiplex shooting that left 12 dead and 58 wounded during a showing of the new Batman film were relived this week at a preliminary hearing of the accused gunman, former grad student James Holmes. "Gangster," based on the non-fiction book of the same name by Paul Lieberman, depicts a battle between a small group of Los Angeles cops who secretly take on Cohen and his crew to wrestle away control of the city from Cohen's mob. Former Los Angeles Police Department homicide detective Will Beall wrote the script to the film, which also stars Emma Stone, Nick Nolte, Anthony Mackie, Giovanni Ribisi and Michael Pena. Rather than dwelling on connections drawn by others to real-life tragedies, Fleischer sought to underscore positive themes. "I think this movie is about people standing up for their beliefs, doing what's right," he said. It's a celebration of these cops who rid L.A. of organized crime of vice and corruption. And, he added, "It's to honor the memory of these police officers who stood up for justice and didn't allow crime to overtake the city." Brolin, a seventh-generation Californian who plays a cop based on an actual police sergeant named John O'Mara, said he spoke with O'Mara's daughter to glean some insights about the man before creating "a composite character." His own father, 72-year old actor James Brolin, visited the set and recounted to his son personal stories from his days as a 9-year-old boy in Los Angeles during that era and going to the backdoors of Sunset Strip nightclubs "looking for Mickey Cohen." Gosling also had a chance to speak to relatives of his character, Sergeant Jerry Wooters, and learned "a lot of great stories and lot of great details" from Wooters' children. "Apparently when he ashed his cigarettes, he would ash in the cuff of his pants, and at the end of the day he would dump out his cuffs and dump out all his ashes," Gosling said. Still, no one ever expected the kind of eerie parallels that occurred between the movie's theater-shooting scene and the real gun violence on July 20, when a man armed with a semi-automatic rifle a shotgun and a pistol walked into midnight screening of the "The Dark Knight Rises" and sprayed the audience with bullets. In an interview with Reuters TV, Brolin said the scene in question in "Gangster Squad" was "bizarrely similar" to the Aurora event, and praised Warner Bros. for replacing the scene. "The fact that is was as parallel as it was, I think there was no way to keep it in," he said. "The Aurora shooting was an unspeakable tragedy, and out of respect for the families of the victims, we felt it was necessary to reshoot that sequence," Fleischer said. I'm proud of the fact that we did that. I think that we didn't compromise the film or our intent.