Aaron Saucedo, 23, spoke up during a brief court appearance late Monday night after his arrest on suspicion of being the killer dubbed the Serial Street Shooter.
Police announced earlier Monday that Saucedo is the suspect in at least 12 shootings across the Valley that left nine people dead and wounded two others.
Update 8.17pm: A former bus driver arrested over a string of killings that terrorised several neighbourhoods of Phoenix, Arizona, has declared "I'm innocent" during a brief court hearing.
Numerous shootings took place in a predominately Latino neighborhood of the Arizona state capital.
The former bus driver's only other comment was to acknowledge that he understood the objective of the court appearance late Monday night.
Saucedo will be held without bond and his next court date is scheduled for May 15.
Police had been hunting for the man dubbed the "serial street shooter" for almost a year.
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.
Police were able to focus on Saucedo after they learned that he owned a 9mm handgun that he pawned off days after the murder.
The Maricopa County attorney, Bill Montgomery, said his office planned to review the evidence and evaluate which charges to pursue in order to prepare the strongest case possible against Saucedo.
A prosecutor says some information about the arrest of a Phoenix man accused in a series of fatal shootings is being withheld from the public because the case remains under investigation.
Witnesses described the shooter as a young, lanky Hispanic man who drove a BMW, helping develop a sketch that bears a striking resemblance to Saucedo.
Police said the killings were unrelated to a series of 2015 freeway shootings in Phoenix that terrified drivers.
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Castro-Garcia, 19, was shot and killed on June 10, 2016, when five of the victims were shot within a 10-day period.
A $75,000 reward will be paid, police spokesman Sgt. Jonathan Howard said.
Police booked 23-year-old Aaron Saucedo on 26 separate felony counts, all related to shootings from 2015 and 2016.
Aaron Saucedo pleaded not guilty at his arraignment on a single murder charge on Friday.
One of the nine people was a 61-year-old man killed in August 2015 whom Saucedo knew through his mother.
Another series of shootings previous year put Phoenix on edge, but Williams said there's no evidence to connect Saucedo to the I-10 Freeway Shootings.
Castro Garcia, 19, was killed on June 10, 2016. "But my son is not coming back". "The pain is the same".
Castro said her son was a noble person who studied and worked hard and was loved by everyone he knew. She said her husband and his friends began hanging out in the backyard instead of the front after the shootings.
Smith was pregnant with the couple's child when Verdugo-Sanchez was fatally shot.
Ms Smith said she had grown frustrated over the past year as detectives kept her in the dark about the investigation. However, they said, none of the evidence between the two series matched. In addition to Romero's murder, he was charged with the seven homicides that made up the original pattern, and a ninth slaying that had not previously been linked to the serial murders - the fatal shooting of Jesse Olivas, 22, on January 1, 2016. Saucedo struck again the following day, shooting a 21-year-old man who also lived, according to reports.
The next shooting did not happen until April 1 2016, when Mr Verdugo-Sanchez was fatally shot.
The majority of Saucedo's alleged attacks took place a year ago when seven were shot dead and two others were wounded over a four-month period - March to July - in a predominately Latino neighborhood in the Phoenix area.