DENVER - Colorado Governor John Hickenlooper delayed the execution of convicted killer Nathan Dunlap Wednesday, citing doubts about death penalty.

Hickenlooper granted Dunlap an indefinite reprieve.Under a reprieve, Dunlap could conceivably be executed some day. The reprieve will stay in place until Hickenlooper or another governor lifts it.

READ:Executive Order D 2013-006

The governor says it's unlikely he'll ever allow the execution.

"We heard from a variety of sides, and obviously this has weighed heavily on me for over a year now," the governor said "It's obvious that inaction wasn't an action."

The next governor can carry out the execution or commute the sentence to life without parole or do nothing and keep Dunlap in solitary.

That means no finality for the families of the victims of the Chuck E Cheese shooting.

"It's not a perfect decision and I recognize that," Hickenlooper told 9NEWS. "I think the reasons that we are doing this, this way, override that lack of closure. I think there still is closure, right? The only thing that's going to happen is something that's going to happen far off and most likely without a lot of fanfare, which is what really they objected to the most."

Arguably the most difficult decision of his political career, Hickenlooper's decision may earn him blowback as prosecutors are currently seeking the death penalty against James Holmes for the mass murder at an Aurora movie theater.

The death toll in the Dunlap case is not as high as the 2012 Aurora theater shooting, but it shares similarities. Dunlap was convicted in 1996 of killing four employees at a Denver-area Chuck E. Cheese restaurant in 1993. The jury sentenced him to die. His last guaranteed appeal was rejected this year. His execution was scheduled for August 2013.

"I am deeply respectful of the suffering and the loss that occurs," Hickenlooper said. "But it's hard to see, from a system-wide perspective, the benefit of a capitol punishment system if it results in 15 to 20 years of legal process and parole, and creates and extends emotional hardship for those families."

Dunlap is not the only inmate on death row. The two other men awaiting death are there for murdering the son of state Rep. Rhonda Fields' (D-Aurora) son and his fiancee.

Fields vehemently opposes ending the death penalty.

District Attorney George Brauchler, who represents the 18th District where the Chuck E. Cheese massacre occurred, held an afternoon demonstration on the Capitol steps along with other supporters of the death penalty.

Brauchler said Hickenlooper'sdecisionwas not justice and that the governor "shrugged" off his responsibility.

"One person will go to bed with smile on his face and that's Nathan Dunlap," Brauchler said."And that's due to one person: Gov. Hickenlooper."

READ:Reaction to governor's decision mostly critical

Bob Crowell, the father of Sylvia Crowell, killed at the Aurora Chuck E. Cheese, was disappointed in the governor's decision.

"We've waited an awful long time," Crowell said. "It's a little like carrying a knife in my back. Today, that night was severely twisted."

Hickenlooper says Colorado's capital punishment system is flawed and the state doesn't have the drugs in place to carry out an execution by lethal injection.