Aaron Saucedo, 23, was arrested in April and later charged with murder in connection with the first of the killings, which occurred in August 2015, Phoenix Police Chief Jeri Williams told reporters at a news conference.
The targets of the serial shooter included men, women and children, many of them ambushed near their homes, between August 2015 and July 2016.
Castro Garcia, 19, was killed on June 10, 2016.
But in a unusual quirk, the Department of Public Safety said Saucedo's gun from the killing of his mother's friend had been test-fired as part of the freeway shooting probe.
Marina Smith, the partner of 21-year-old Diego Verdugo-Sanchez, who was gunned down on April 1, 2016, said she welcomed news of the arrest but was still grappling with his death.
They also tied Saucedo to the January 2016 murder of 22-year-old Jesse Olivas - and seven other fatal shootings already identified as part of the pattern, police said.
Police said the killings were unrelated to a series of 2015 freeway shootings in Phoenix that terrified drivers.
With Obamacare vote, House Republicans free to turn to tax reform
The discussion often reveals an assumption that we are just buying a service and paying for it much as we finance a new auto . He had worked as a young staffer in the Reagan administration and once chaired a House committee that oversees health care.
Saucedo faces the possibility of more than two dozen criminal charges, including murder, attempted murder and aggravated assault, Williams said. That string involved nine shootings and seven deaths, bringing the total accusations against Saucedo to 12 shootings and nine homicides.
Police say the shooter stalked the streets with a handgun after dark, picking victims who were either outside of their homes or sitting in cars. Authorities say Saucedo did not know the other victims.
Police arrested Saucdeo in that case after finding a pistol he'd sold at a pawn shop and matching it to evidence found at the crime scene, court documents said.
A serial killing suspect accused of fatally shooting seven people a year ago and wounding two others in attacks that terrorized a largely Latino Phoenix neighborhood was arrested Monday, authorities said.
Phoenix police announced Monday afternoon that 23-year-old Aaron Juan Saucedo was taken into custody in connection with the case that authorities said was the work of a serial killer.
Another series of shootings a year ago put Phoenix on edge, but Williams said there's no evidence to connect Saucedo to the I-10 Freeway Shootings.
- Trump's First Foreign Trip As President Is Later Than Anyone Since LBJ
- After UNESCO Jerusalem vote, Israel cuts UN funding
- Wenger narrowly missed out on signing Mbappe
- Brokerages Set Enable Midstream Partners LP (ENBL) Price Target at $15.86
- Top Bears Draft Pick Mitchell Trubisky Picks Jersey Number
- A look at the House Republican health care bill
- Britain awaits local election results in test for PM
- Could The Health Care Vote Cost Republicans The House Majority?
- 2 killed when cargo plane goes off runway in West Virginia
- 'Guardians' sequel blasts off to $17M on opening night