PHOENIX — The former city bus driver arrested in a string of 2016 serial killings that terrorized several Phoenix neighborhoods declared “I’m innocent” during a brief court hearing.

Aaron Saucedo, 23, appeared before a judge late Monday night and acknowledged that he understood the purpose of the court appearance to inform him of the allegations.

“I’m innocent” were the only other words he spoke during the appearance before a judge who agreed with a prosecutor that Saucedo should be held without bond.

Police say Saucedo killed nine people and carried out 12 shootings from August 2015 and July 2016, targeting victims after dark and gunning them down as they stood outside their homes or sat in their cars. Most of the killings happened in a largely Latino neighborhood.

Police fielded thousands of tips, went door-to-door in seeking information and analyzed ballistics from a different, unrelated serial shooting case.

On Monday, they announced they had arrested Saucedo while providing scant detail about what motivated him or details about how they made a break in the case, other than to credit tips.