Megan Cassidy and Michael Kiefer

The Arizona Republic

PHOENIX — Police had been eyeing Aaron Juan Saucedo as a suspect in the Phoenix "Serial Street Shooter" investigation for nine months before he was officially tied to the case on May 8, threading together a web of information that included witness statements, ballistics evidence and surveillance footage, a previously withheld court record shows.

Fifteen shell casings were found in two vehicles that Saucedo had been driving. Police say they have since linked them to the spree of unsolved murders that have rattled Phoenix for months.

Acting on a judge’s recent order, the Maricopa County Attorney’s Office on Friday filed a redacted version of a public record that until then had been sealed by the court.

The record, known as a Form IV, offers the first glimpse at the investigation that tied 24-year-old Saucedo to one of Phoenix’s most prolific killing sprees — nine homicides in a matter of 11 months.

Police offered scant investigative details when they announced Saucedo’s arrest, only divulging the types of evidence that they say tied him to the crimes.

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The newly released court record states that two witnesses initially brought Saucedo to detectives’ attention on Aug. 7 and Aug. 31. The witnesses said Saucedo looked similar to the composite image police had recently circulated of the suspected shooter. They also noted he recently stopped driving a black BMW after police said the killer had been driving a similar car, and that Saucedo had begun growing out facial hair.

The document additionally filled in details on ballistic links to the case. On April 22, an unnamed witness turned over a handgun that Saucedo’s father had confiscated from him “for safety concerns.” The handgun was said to be a Bryco Arms .380 caliber, which police say later was forensically linked to the shooting death of Jesse Olivas.

The Form IV also revealed that there were 14 shell casings found in a 2003 Hyundai Sonata that Saucedo owned at the time of the murders, and one shell casing found in his black BMW. Police said 13 of the 9mm casings in the Sonata, as well as the 9mm casing in the BMW, were fired by the same gun that left casings at nine of the crime scenes. The remaining shell casing found in the Sonata was a .380.

And through pawn shop records, police say they can place Saucedo in possession of three guns at the times they were reportedly used in the crimes linked to the street shooter.

Saucedo purchased a High-Point 9mm gun from a pawn shop on July 2, 2015, and sold it on Sept. 1, 2015. In the interim, police say that exact weapon fired the casings found at a residence hit by several bullets on Aug. 12, 2015, and in the murder of Raul Romero on Aug. 16, 2015.

On the same day Saucedo sold the High-Point 9mm, police said he purchased the Bryco Arms .380. That gun, according to ballistics tests, was the weapon used to kill Olivas on Jan. 1, 2016.

Police said Saucedo purchased another 9mm handgun on Feb. 21, 2016, which would have fit the timing of nine other incidents between March and July 2016. The Form IV did not indicate whether detectives are in possession of this weapon.

Police said Saucedo admitted to detectives that he drove a black 2001 BMW 540i between May and August 2016, a car that was consistent with video footage from the final incident.

His family has declined multiple requests for comment from The Arizona Republic.

To date, Saucedo has only been officially charged with one of the homicides. He was rebooked in connection with the rest of the crimes, and he declared his innocence at a preliminary court appearance.

Police are additionally recommending the following charges:

• First-degree murder, eight counts.

• Discharging a firearm at a residence.

• Drive-by shooting, six counts.

• Aggravated assault with a deadly weapon, three counts.

• Attempted first-degree murder, three counts.

• Aggravated assault causing serious physical injury, two counts.

• Discharging a firearm at a non-residence.

• Endangerment.

• Criminal damage.