05/14/2013 02:05 pm ET Updated May 14, 2013

George Brauchler, Arapahoe County District Attorney, On Clemency Appeal: 'Justice Demands The Death Of Nathan Dunlap'

While the governor has heard arguments from convicted death row inmate Nathan Dunlap's attorneys asking to spare his life, he's also been called to consider why Dunlap was sent there in the first place.

Arapahoe County District Attorney George Brauchler wrote an impassioned 32-page rebuttal to Dunlap's clemency appeal last Friday calling on Governor John Hickenlooper to "show courage" and let Dunlap face his execution, which has already been set for the week of Aug. 18.

"This is a matter of justice, and justice demands the death of Nathan Dunlap," Brauchler told 9News.

The jury foreman from Colorado's last death penalty case also wrote to the governor, arguing for a clemency denial.

We wept over our decision... I trust the Dunlap jury took the same care and concern we did. Now is your chance to show you were serious about mass shootings in Colorado, and not merely offering up my state as some sort of gun control trophy.

Brauchler's rebuttal also called arguments about race playing a role in the imposition of the death penalty in Colorado "vile, disgusting and offensive."

Lawyers for Dunlap filed a formal petition for clemency to the governor earlier last week asking that his sentence be commuted to life without parole rather than death.

Dunlap's attorneys argued that their client had undiagnosed bipolar disorder in 1993, the year Dunlap walked into an Aurora Chuck E. Cheese restaurant and fatally shot three teenagers and a manager. A fifth person, Bobby Stevens, was injured and survived. Three years later at the age of 22, Dunlap was convicted and sentenced to death.

In February however, the U.S. Supreme Court declined to hear Dunlap's appeal and this month -- after spending 17 years on death row -- a judge ruled that Dunlap be executed the week of Aug. 18.

Now Democratic Gov. John Hickenlooper is left with the final say.

"It's a hard one. It's as hard as it gets," Hickenlooper told the media on Monday outside the Capitol.

The governor has been meeting with Dunlap's defense team, victims' family members and prosecutors but has told reporters that he remains conflicted about whether or not to exercise his power to grant clemency.

However rumors in Colorado's more conservative blogosphere that the governor might be leaning toward clemency picked up steam last week when Hickenlooper's chief of staff, Roxane White, sent out some suggestive Tweets.

White also Tweeted that all of Colorado's death row inmates are from the same judicial district and "all African American men from the same high school" before linking out to the International Commission Against Death Penalty.

“My cabinet are about half and half,” Hickenlooper said Monday. “Maybe about 60 percent oppose the death penalty, 40 percent support it.”

The petition says jurors did not know about Dunlap's mental health disorder when they convicted him.

Click here to read Nathan Dunlap's whole petition for clemency.

“Nathan Dunlap’s childhood was characterized by extreme physical, emotional and sexual abuse. The jury that sentenced him to death knew nothing of his serious mental illness, or the role of that illness in his commission of the murders. Nathan Dunlap – then 19 years old – was in the grip of his first full-blown manic phase when he committed his terrible crime," the petition read.

Bob Crowell, the father of 19-year-old Sylvia Crowell who was killed in the shootings, told The Denver Post that he estimated three-quarters of the victims' family members remain in favor of execution.

In a video released by his attorneys, Dunlap says he regrets what he did and that he wrote letters to his victims' families.

"It's my understanding that some people perceive the letters as being cold. I can't dispute that because I didn't know if these people wanted to hear from me. I want to talk to them, for them, not for me. I don't want to cause Bobby Stephens, anybody, anymore pain that I've already caused," Dunlap said.

Dunlap's attorneys are also challenging the constitutionality of the death penalty, arguing that it's cruel and unusual punishment to make inmates wait on death row for decades for a possible execution date. The judge set a June 10 hearing to hear Dunlap's attorneys' arguments.

But, the petition says, "One thing is certain: Mr. Dunlap will never leave prison alive."

Dunlap is set to become the first prisoner to be executed in Colorado in 16 years, since the execution of convicted killer and rapist Gary Davis in 1997 by lethal injection.

Dunlap is one of three men on Colorado's death row -- all of whom were convicted in Arapahoe County -- and Brauchler said his office is seeking the death penalty for suspected Aurora shooter James Holmes as well.