"He didn't give 12 people the chance to plea bargain and say, 'Let's see if you're going to shoot me or not,'" said Cowden, whose two teenage daughters were with their father when he was killed.
"No. No plea bargain," she said.
The attack during a crowded midnight showing of "The Dark Knight Rises" left a dozen people dead and 70 injured.
Prosecutors have said Holmes planned the assault for months, casing the theater complex in the Denver suburb of Aurora, amassing a small arsenal and rigging potentially deadly booby-traps in his apartment.
Then on July 20, he donned a police-style helmet and body armor, tossed a gas canister into the theater crowd and opened fire, prosecutors said.
The plea offer, made by Holmes' lawyers on his behalf sometime before March 12, was disclosed a defense court filing on Wednesday. It was made public just days before the prosecution was set to announce whether they would seek the death penalty.
The filing didn't include the specifics of the offer. It said only that Holmes would agree to life in prison without parole instead of the death penalty and didn't mention any other concessions.
Pierce O'Farrill, who was shot three times, said he would welcome an agreement that would imprison Holmes for life. The years of court struggles ahead would likely be emotionally stressful for victims, he said.
"I don't see his death bringing me peace," O'Farrill said. "To me, my prayer for him was that he would spend the rest of his life in prison and hopefully, in all those years he has left, he could find God and ask for forgiveness himself."
Tom Sullivan, whose son Alex was killed, said he has wanted prosecutors to pursue the death penalty. But he said he wouldn't object to a plea agreement if it avoided a lengthy court battle and if Holmes got no privileges in prison.
"That was kind of a sore point with us," he said, referring to privileges such as outside exercise or listening to music. "We didn't think this kind of person should have any kind of privileges except the bare essentials."
Holmes, a former graduate student at the University of Colorado, Denver, had seen a psychiatrist at the school before the shootings.
His lawyers have said he was taken to a hospital psychiatric ward in November because he was considered a threat to himself. Holmes was held there for several days and spent much of the time in restraints.
In their court filing, Holmes' lawyers again said they were exploring a plea of not guilty by reason of insanity and would mount a vigorous defense if prosecutors rejected the plea offer and the case goes to trial.
Holmes was widely expected to enter an insanity plea at his arraignment on March 12, but his attorneys told District Judge William Sylvester they had too many questions about the constitutionality of Colorado's death penalty and insanity statutes to advise Holmes on how to plead.
Sylvester then entered a plea of not guilty on Holmes' behalf but said he could change it later to insanity if he chose.
The judge scheduled the trial to start Aug. 5, setting aside four weeks.
Doug Wilson, who heads the state public defenders' office, told The Associated Press on Wednesday that prosecutors haven't responded to the offer. He didn't know whether prosecutors had relayed the offer with any victims as required by state law.
Prosecutors declined to comment on Wednesday.
Dan Recht, a past president of the Colorado Criminal Defense Bar, said prosecutors likely started talking to victims long ago.
"The defense, by making this public pleading, is reaching out to the victims' families," Recht said.
Also Wednesday, Sylvester denied a request from New York-based Fox News reporter Jana Winter to delay a Monday hearing where she has been ordered to testify about her sources for a story about Holmes.
Winter cited unnamed law enforcement officials saying Holmes sent drawings that foreshadowed the attack to a psychiatrist. Holmes' lawyers contend that whoever spoke to Winter violated a gag order.