Authorities originally thought Orduno might have been hiding somewhere at the sprawling jail, which also houses Arpaio's famous "tent city" lockup. But jail personnel searched the 600,000-square-foot complex and determined Orduno wasn't here.
The entire facility, which holds about 2,000 inmates, was placed on lockdown once detention officers discovered Orduno wasn't in his cell, the Arizona Republic reported. Authorities also warned the public to be on the lookout for Orduno, whom the sheriff described as a violent "troublemaker."
Orduno has served time in state prison for burglary, theft and aggravated assault, online state records show.
He was being held at the Maricopa County jail on attempted murder and robbery charges. The Republic reported the charges stemmed from an October 2011 robbery at a Phoenix jewelry store that led to a police chase in which either Orduno or an accomplice fired at pursuing officers. No one was injured.
Orduno had been in custody since Phoenix police arrested him Nov. 4, 2011, and he recently was declared competent to stand trial.
Deputy Chief Brian Lee, another sheriff's spokesman, said the cell that Orduno occupied at the jail's psychiatric ward had a small window. Detention officers look through the windows every 15 minutes to check on inmates, per department protocol, he said.