PHOENIX >> The man arrested in a string of serial killings left behind shell casings at several scenes that authorities tested and linked him to the crimes, police said in documents released today that provide the most detailed narrative to date about a case that unnerved Phoenix neighborhoods last year.

The documents were released after media organizations went to court in a bid to get prosecutors to unseal the evidence that led to the arrest of 23-year-old Aaron Saucedo in nine killings.

Police say that in one of his killings, Saucedo opened fire on a man walking along a Phoenix street on New Year’s Day 2016 and then got out of his car and kicked him twice before calmly driving away. The documents also say surveillance video captured from a July 2016 shooting scene determined the shooter’s car was a 5-series BMW — the same model that Saucedo drove.

Saucedo emerged as a possible culprit just weeks after the last of the nine shootings. Two witnesses told authorities in August 2016 that Saucedo matched a composite sketch of the suspect and drove a BMW similar to one seen at the crimes. Homicide detectives interrogated him in December, about five months before he was arrested.

In the interview, Saucedo told authorities he drove a BMW and owned a 9mm handgun, which he said had been stolen.

Saucedo told a judge last week “I’m innocent” in the hours after he was arrested.

Police say Saucedo randomly opened fire on people after dark, primarily in a largely Latino neighborhood in Phoenix. Many residents reacted by staying inside after dark as police fielded thousands of tips.

Police say his victims include a 21-year-old man whose girlfriend was pregnant with their son and a 12-year-girl who was shot to death along with her mother and a friend of the woman. No motive has been established. Saucedo only knew one of the victims.