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James Holmes, the man who killed 12 people inside an Aurora movie theater two years ago, is “a human being gripped by a severe mental illness,” his parents write in a letter that pleads for him to be spared from execution.

“We have read postings on the Internet that have likened him to a monster,” Robert and Arlene Holmes write in the letter. “He is not a monster.”

The letter, provided to The Denver Post, is the first time Holmes’ parents have commented publicly about their son’s actions and about the grief they have felt as a result. The Holmeses write that they have “spent every moment for more than two years thinking about those who were injured and the families and friends of the deceased.”

“We are always praying for everyone in Aurora,” they write. “We wish that July 20, 2012, never happened.”

The letter comes as 9,000 jury summonses are being delivered for their son’s trial. Jury selection is scheduled to begin Jan. 20. Opening statements for the months-long trial likely won’t begin until late May or early June.

Holmes is charged with murdering 12 people and attempting to murder 70 others inside the Century Aurora 16 movie theater in what was one of the worst mass shootings in American history. Killed in the attack were Jonathan Blunk, A.J. Boik, Jesse Childress, Gordon Cowden, Jessica Ghawi, John Larimer, Matt McQuinn, Micayla Medek, Veronica Moser-Sullivan, Alex Sullivan, Alex Teves and Rebecca Wingo.

Victims’ family members reached Thursday evening declined to comment on the letter. One victim’s relative questioned the timing of the letter — coming so close to jury selection — but did not want to say more for fear of hurting the trial’s integrity.

Prosecutors are seeking the death penalty — “In this case, for James Eagan Holmes, justice is death,” Arapahoe County District Attorney George Brauchler announced in April 2013.

The following month, Holmes’ attorneys said for the first time that one of their expert witnesses had diagnosed Holmes with a severe mental illness. Holmes subsequently changed his plea to not guilty by reason of insanity.

The letter does not reveal new details about Holmes’ diagnosis or his actions in the months leading up to the shooting, when prosecutors contend he stockpiled weapons, ammunition and explosives. It does not disclose the findings of two critical court-ordered sanity exams that likely will be at the heart of the trial.

Instead, the Holmeses use the letter to make two arguments: that their son should be sentenced to life in treatment, not death, and that taking the case to trial “will cause everyone to relive those horrible moments in time, causing additional trauma.”

Robert and Arlene Holmes write that, prior to the theater attack, their son “never harmed anyone and he had no criminal history.” They say they hope he is found not guilty by reason of insanity and sentenced to a mental health institution for the rest of his life, something they say “would prevent any future harm to him and others.”

They use one paragraph of the letter to point to the work of two groups — the Murder Victims’ Families for Human Rights and the National Alliance on Mental Illness — that argue against executing the mentally ill.

“We love our son, we have always loved him and we do not want him to be executed,” they write.

Short of institutionalization, they urge attorneys in the case to negotiate a plea deal that would send Holmes to life in prison without the possibility of parole. Such a deal would avoid a lengthy trial, which the judge overseeing the case has allowed to be broadcast live.

The effort to avoid trial echoes one defense attorneys made early in the case, when they announced in a court filing that Holmes had offered to plead guilty in exchange for prosecutors dropping the death penalty. Prosecutors responded that the defense was withholding information they needed to assess the plea offer, making it “extremely unlikely” that they would reach a deal.

The Holmeses — Robert is a scientist, and Arlene is a nurse — have made frequent trips from their home in San Diego to Colorado for their son’s court appearances. Often, they sit quietly side by side, speaking to one another infrequently in court and almost never appearing to try to catch their son’s gaze.

The Post’s editorial page obtained the letter through the Holmeses’ attorney, Lisa Damiani. Aside from a brief comment to a reporter on the morning of the shootings and a clarifying statement issued through their attorney, Holmes’ parents have never before commented publicly about the attack. They close their letter by writing that they have avoided interviews because they do not want to take attention away from the shooting’s victims.

“We mourn the deaths and the serious injuries and emotional trauma of the others who were in the theater,” they write. “The focus should be on the injured and their healing.”

John Ingold: 303-954-1068, jingold@denverpost.com or twitter.com/johningold