Joshua Waring, son of former "Real Housewives of Orange County" star Lauri Peterson, did not have gunshot residue on his hands or clothing after his arrest in connection with a Costa Mesa shooting last year, according to an analysis performed by the Los Angeles County Department of Medical-Examiner Coroner.
However, forensic experts cautioned against drawing the conclusion that the analysis supports Waring's claim that the test results could exonerate him of attempted-murder charges.
Such tests are performed to help determine whether a suspect recently fired a gun.
Waring, 28, has been in Orange County Jail for 10 months in connection with a drive-by shooting in June outside a home in the 2900 block of Babb Street that left a man severely injured.
Waring said during a jailhouse interview with the Daily Pilot last week that the results of the gunshot-residue test, which he said was administered after his arrest, could exonerate him. Waring received the results Monday.
However, Debra Gibson, acting chief of forensics laboratories for the Los Angeles County coroner's office, wrote in the analysis report, dated in February, that the findings are inconclusive.
And Michael Martinez, a forensic scientist supervisor at the Bexar County Crime Laboratory in Texas, said Thursday that "gunshot residue is nothing more than an investigatory tool."
"Getting an exoneration because gunshot residue can't be found is a huge leap," Martinez said in a phone interview.
No single piece of forensic evidence should be used to draw a major conclusion in a particular case, Martinez said. "It is only to provide assistance to establish or corroborate a narrative," he added.
The Orange County district attorney's office declined to comment about the results.
Martinez, who has not analyzed any gunshot residue samples in Waring's case, likened the process of collecting such residue from a suspect to finding a ping pong ball on a football field.
Gunshot residue's consistency is similar to that of flour or dust, meaning that wiping or washing hands can easily dislodge the particles, experts say.
"It's hard to find," Martinez said.
Typically, he said, gunshot residue is collected for testing by dabbing adhesive carbon tape on a person's hands and clothing. The sample is run through a scanning electronic microscope using software that searches for elements found in gunshot residue.
Experts say there's a variety of reasons that residue might not be found on a person's hands even if the person had fired a gun.
The person could have been wearing gloves, washed or wiped his or her hands or otherwise caused the particles to become dislodged, according to the report and Martinez.
The type and caliber of the gun used can play a role in how much residue is left behind, Martinez said.
Another factor is the amount of time between the shooting and when the sample was collected. Martinez said the ideal window for collecting gunshot residue is within four to six hours after the gun was fired.
"That doesn't mean we can't find any … after six hours," Martinez said. "It just means that's the window where it's most likely to be found."
Waring was arrested about eight hours after the shooting.
Authorities have alleged that he showed up at the Babb Street house in a
An Orange County Sheriff's Department helicopter crew saw the BMW, and police followed it through Santa Ana before it crashed into another vehicle, authorities said.
Santa Ana police said in court that Waring ran and hid in the restroom of a nearby business before surrendering to officers.
During a preliminary hearing last year, Waring told Orange County Superior Court Judge W. Michael Hayes that he fled from police because he was heading to pick up drugs.
Waring faces three counts of attempted murder, one count of unlawfully discharging a firearm at an inhabited dwelling, three counts of assault with a firearm, a count of vehicle theft, a count of shooting at another person from a motor vehicle and a count of evading police while driving recklessly, all felonies.
He also faces misdemeanor charges of battery, resisting an officer and hit-and-run with property damage, along with possible sentencing enhancements on allegations of personal use of a firearm and inflicting great bodily injury.
If he's convicted at trial, Waring could end up in prison for the rest of his life.
He proclaimed his innocence during the interview with the Daily Pilot.
"I know myself and I know I wouldn't do this," he said.
Waring is due back in court for a pretrial hearing June 14.
His mother was a cast member of Bravo's reality TV series "The Real Housewives of Orange County" from its debut in 2006 until 2008.