Trials of two of Arizona's most notorious serial killers relying on evidence not everyone trusts
Phoenix, Arizona: Two of the most high-profile criminal cases in Arizona are heading toward important court proceedings, where the reliability of ballistic evidence is set to play a central role. Aaron Saucedo and Cleophus Cooksey Jr, two men accused of committing serial shooting sprees that left multiple victims dead, will face trials in early 2025.
Who is Aaron Saucedo?
Aaron Saucedo, also known as the 'Serial Street Shooter', is a convicted criminal linked to a series of shootings that occurred in Phoenix between 2015 and 2016. Saucedo was arrested in 2017 and charged with multiple counts of murder, assault, and other crimes. He is accused of carrying out at least nine fatal shootings and numerous other attacks in the Maryvale neighborhood and other areas of Phoenix. Authorities used ballistic evidence and witness statements to link Saucedo to the crimes.
Who is Cleophus Cooksey Jr.?
Cleophus Cooksey Jr. is a convicted murderer who was linked to a series of killings in the Phoenix area in late 2017. Cooksey was arrested in December 2017 after a shooting incident involving his mother and stepfather. During the investigation, authorities connected him to a total of nine homicides that had taken place between November and December 2017.
Cooksey's alleged crimes were particularly shocking because of their brutality and the short time span in which they occurred. He targeted a variety of victims, and the killings appeared to lack a consistent motive, which made the case even more complex for investigators.
Even before these crimes, Cooksey had a history of violent offenses and had served time in prison. Cooksey was charged with multiple counts of first-degree murder and other related offenses.
Jason Lamb, an Arizona defense attorney not involved in these cases, told Arizona's Family that the trials are likely to heavily rely on ballistic evidence. He points out that if this evidence connects the bullets to Saucedo and Cooksey, it could be a decisive factor for the prosecution.
However, the reliability of ballistic evidence is not without its controversies. Ballistic analysis often involves comparing the markings on bullets or cartridge casings found at a crime scene with those from a suspect's firearm. These markings are assumed to be unique to each gun, similar to fingerprints. However, the interpretation of these patterns can be subjective. Different analysts might come to different conclusions when examining the same evidence, leading to inconsistencies in results.
The field of forensic ballistics lacks a universally accepted set of standards and guidelines. Techniques and methods can vary from one lab to another, which can influence the outcomes of analyses. This lack of standardization can raise questions about the reliability of the evidence presented in court.
Tool marks, which are the scratches and impressions left on bullets or casings when they are fired, are often used to link a bullet to a specific gun. The problem is that these marks are not always as unique as previously believed, and similarities between different firearms can lead to incorrect matches.
Research has shown that ballistics experts can make errors in their assessments. Studies have demonstrated that false positive rates—where an analyst incorrectly matches a bullet to a firearm—are not negligible. The lack of rigorous scientific validation has led some critics to argue that ballistic evidence does not meet the standards of a truly reliable forensic science.
Although technology has improved in recent years, ballistics still relies heavily on visual comparisons, which are prone to human error. Automated systems like the National Integrated Ballistic Information Network (NIBIN) can assist, but they do not eliminate the need for human interpretation. Even with advanced imaging techniques, there is still no guarantee that the analysis is infallible.
Ballistic experts can be influenced by cognitive biases, especially when they know other details of the case that might sway their judgment. This is known as confirmation bias, where an expert might interpret evidence in a way that supports a preconceived belief or expectation. Efforts to blind analysts from case details have been recommended but are not always implemented.
In US courts, the admissibility of scientific evidence is often evaluated based on the Daubert standards, which require that the methodology used be tested, peer-reviewed, have a known error rate, and be generally accepted in the scientific community. Critics argue that ballistic evidence does not consistently meet these criteria, leading to legal challenges over its admissibility in court.
The next phase in the Saucedo and Cooksey cases will involve several days of oral arguments from both sides, set to begin in mid-November. During these sessions, the judge will decide whether to proceed with an evidentiary hearing on the admissibility of the ballistic evidence. Saucedo's trial is scheduled to begin in February 2025, while Cooksey's trial is set for April 2025.