PHOENIX -- A man was convicted of first-degree murder Monday in the vicious beating death of another inmate in Maricopa County's Fourth Avenue Jail.

Jurors will return to court Thursday to start hearing evidence about whether Pete Van Winkle, 27, should be eligible for the death penalty in the May 1, 2008, slaying of Robert Cotton, 28.

Scott Appelbe, Cotton's brother, said he was "dumbfounded" about the situation, and "happy justice was being served."

Prosecutors said the key piece of evidence against Van Winkle, who is described as a member of the Aryan Brotherhood in an initial report from the Maricopa County Sheriff's Office, was a graphic surveillance tape that showed most of the strangulation and beating of Cotton.

The slaying raised questions about security in the jail because the attack went unnoticed by detention officers for more than 15 minutes.

The county eventually paid $500,000 to settle a $2 million claim filed by Cotton's family.