The management of a Colorado movie theater where 12 patrons were slain in a 2012 shooting rampage could never have foreseen, nor safeguarded against, such a seemingly random but meticulously planned and violent attack, its lawyers said on Wednesday.

Towards the close of the first civil trial of wrongful death and personal injury claims stemming from the mass shooting, attorneys for Cinemark USA Inc told jurors that liability for the carnage rested mainly with the convicted gunman, James Holmes, and not theater owners.

The lawyers also put some responsibility on two University of Colorado psychiatrists who had treated Holmes and should have known he was a danger to others, and on a police officer alerted to Holmes' violent predisposition who failed to act on the tip.

Cinemark's closing arguments in the lawsuit against the Texas-based theater chain, filed by more than two dozen surviving victims and relatives of the dead, capped a week of testimony in Arapahoe County District Court.

Lawyers for the plaintiffs argued that Cinemark and its co-defendants, the theater's property owners, should be held liable for various security lapses they say contributed to the tragedy at the Century 16 Theater multiplex in Aurora, Colorado.

Holmes, who pleaded innocent by reason of insanity at his murder trial, was found guilty last summer of killing 12 people and wounding 70 when he opened fire during a midnight premiere screening of the Batman film, "The Dark Knight Rises", on July 20, 2012. He was sentenced to life in prison.

Jurors were to begin deliberations on Thursday.

If the panel finds Cinemark liable, a second jury will be chosen to decide how much responsibility the company should bear and thus how much it should pay. If Cinemark is found not liable, the case is over.

Wrapping up their case on Wednesday, defense lawyers played a slide show of photographs showing Holmes' booby-trapped apartment, his weapons and his body armor.

"How can it be said that Cinemark could have foreseen this?" Cinemark attorney Kevin Taylor asked as he gestured to the screen.

Plaintiffs' lawyer Marc Bern said Cinemark should have done more to protect its patrons.

He cited the absence of a silent alarm on the rear exit door through which the gunman launched his attack, or of security cameras. He also faulted Cinemark for failing to post armed guards inside the cinema or security patrols outside.