PHOENIX -- In May 2008, Maricopa County Jail inmate Pete Van Winkle killed fellow inmate Robert Cotton after a beating that lasted 15 minutes, possibly because Cotton refused to beat up another inmate for the Aryan Brotherhood, of which deputies said Van Winkle is a member.

A jail surveillance camera captured the incident on tape.

Van Winkle has since been charged with first-degree murder.

One question remains: Could this killing have been prevented? Deputies said no.

In a press conference held Wednesday afternoon, the sheriff's office accused CBS 5 of manipulating the footage of the beating.

"That video, shown on Channel 5 on two different nights, was technically enhanced by the TV station and does not accurately reflect what any detention officer could have observed on the night of the murder," said MCSO Chief Jerry Sheridan.

In fact, CBS 5 showed the video both in its original form and, at times, isolated or zoomed into particular scenes. Everything seen on that video was recorded by the jail cameras.

According to deputies, there are more than 30 camera angles that can be monitored on several screens in the jail's tower.

The guard on duty at the time of the slaying did not have the surveillance footage from that angle up on his monitors; in fact, he did not know there was a problem until after Cotton's body was dragged onto the walkway, deputies said.

In addition to watching the monitors, the guard was talking on the phone with another officer, Sheridan said.

"The officer in the tower was performing his duties the way we trained him," Sheridan said. "He was on the phone; he was looking at monitors."

At the time of the slaying, only five inmates were allowed out of their cells; the tape shows Van Winkle and Cotton in the cell and another man in the shower, leaving only two inmates on the guard's monitors.

Nevertheless, Sheridan said that it was not unusual for three out of five inmates to be out of sight.

"Their cells are open," he said. "They don't have to come out for their four hours. They can if they want; we give them that opportunity. We give them the opportunity to socialize with each other."

Sheridan also said this was not a staffing issue.

Additionally, when MCSO originally reported the death in its press release, deputies rushed to the scene, but during Wednesday's press conference, Sheridan said it took longer.

"It took 3 1/2 minutes -- not five as reported -- for a team of detention officers to safely respond to a dangerous situation inside the housing unit," he said.

CBS 5 originally reported that it took guards five minutes to reach Van Winkle; however, a closer examination of the video showed it took just over four minutes from when Van Winkle started dragging Cotton out of the cell to the moment guards arrived.

In their 569-page report, Sheriff's investigators concluded that there was nothing the guards could have done to prevent the slaying.

"There was virtually no way that we could have come up with, that we could have prevented this situation except one," said Lisa Allen, a spokeswoman for the sheriff's office. "That would be to put all of our inmates in the facility into 23-hour lockdown -- let them out one at a time, one hour at a time."

Allen said the jail did not and will not implement this measure.

"Had we done that, ACLU attorneys, middle ground attorneys, other civil attorneys would have come against the sheriff's office, as they often do, and say that we're violating inmate rights," she said. "We're in a no-win situation."

Scott Appelbe, Cotton's brother, disagrees.

"For someone to plan and carry out a murder inside a maximum facility, then they need to look at their textbook and make some changes and some adjustments," Appelbe said.