PHOENIX -- Recently obtained surveillance video of a jailhouse slaying contradicts the official report from the Maricopa County Sheriff's Office, 5 Investigates found.

The footage from May 1 shows the slaying of inmate Robert Cotton by another inmate, Pete Van Winkle.

Van Winkle -- who is a member of the Aryan Brotherhood, according to MCSO's report -- has been charged with first-degree murder.

In a press release sent the day after Cotton's death, MCSO claimed "nothing out of the ordinary appeared to be happening in or around that cell," and once Van Winkle dragged Cotton out of the cell, "detention officers rushed to the scene."

The surveillance video shows the beating lasted 15 minutes, during which it appears Van Winkle strangled and punched the other inmate, and jumped on Cotton's head.

Once Van Winkle drags Cotton's body out of the cell, it takes guards five minutes to arrive at the scene.

"Things can happen in the blink of an eye," said Scott Appelbe, Cotton's brother. "Twenty minutes -- that’s not the blink of an eye. That's somebody didn't do their job."

Applebee said Cotton, who was in jail awaiting trial for auto theft -- spoke to him two nights before his death.

"If there was any inkling about him being afraid or someone was after him, he would have told me," Appelbe said.

He said Cotton was never violent, and -- although he was in jail -- he had recently taken steps to turn his life around.

According to the 500-page investigative report prepared by the sheriff's office, Cotton may have been killed because he refused to beat up another inmate for the Aryan Brotherhood.

• READ: MCSO Incident Report Part 1 | Part 2

No matter the reason behind the beating, security consultant Jess Torres said Cotton's death should not have happened.

"Where was the guard that was supposed to be monitoring the camera?" he asked. "That's the biggest question ... Somebody wasn't doing their job."

Torres, a former police officer, said a jail guard should have recognized what was going on.

"They’re trained to notice and they're paid to notice -- so, yes, I believe that they should have noticed," he said.

5 Investigates discovered that the guard in the observation tower who was supposed to be watching the video monitors was on the telephone while the beating took place.

Maricopa County Sheriff Joe Arpaio refused to comment on the case; Cotton's family has filed a claim against the sheriff's office for $2 million.

According to Joe Torres, the sheriff's office knows "what went wrong."

"Now, whether they correct it or not, is going to be something else," Torres said.

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