Phoenix Police Chief Jeri Williams says the arrest brings closure to the mostly Hispanic community.
The gunman's targets included men, women and children, many of them ambushed near their homes in a working-class neighborhood from August 2015 to July 2016. Authorities say Saucedo did not know the other victims.
Saucedo was booked on 26 felony counts, including homicide, assault and drive-by shooting.
"Our hearts go out to the surviving families", Williams said. "Today we are closer to providing them the justice they deserve", Williams said.
The shooter stalked victims after dark, police have said, picking victims who were either outside of their homes or sitting in cars.
The city's fear peaked because most of the killings came in a cluster, with seven people slain in a two-and-a-half-month period last spring.
Saucedo was arrested last month in connection with the August 2015 fatal shooting of a man who had a relationship with his mother, 61-year-old Raul Romero.
As authorities investigated Saucedo more closely, they connected him to the serial killing case.
Saucedo initially was arrested last month in connection with the August 2015 killing.
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A survivor of one shooting told News 12 that after police showed up at his home with photos, he recognized Saucedo's face. All of the killings were random except for the first one, Williams said.
Records show Saucedo was pulled over for allegedly running a red light on October 27, 2015, just a month after the first killing. Police have since linked this murder to the string of street shootings.
Police said they investigated whether Saucedo might be the so-called Phoenix freeway shooter, believed responsible for nearly 12 incidents, none of them fatal, on Interstate 10 in 2015.
She said he preferred playing basketball with friends to partying.
His case was ultimately thrown out however, but investigators still believe he's the culprit.
Police said they have not identified a motive but believe Saucedo acted alone. The Associated Press was unable to reach Saucedo's public defender on Monday.
Police in Phoenix are frustrated.
The first shooting happened on March 17, 2016, when a Nissan drove past two teenagers, pulled a U-turn and a man inside the vehicle opened fire, hitting a 16-year-old boy in the arm, abdomen and hip. The suspect struck again the next day but didn't kill anyone.
Jesse Olivas, 22, was shot dead on the street on January 1, 2016. Castro-Garcia, 19, was fatally shot on June 10, 2016.