PHOENIX — On Jan. 25, 2021, Phoenix officers thought they were responding to a car crash. Instead, they found Anthony Martin shot to death in a red Buick that was tipped half-up on another vehicle in a parking lot.
Almost three years later, his murder is still unsolved.
It’s just one of many cases impacted by the mistakes and investigative breakdowns of former Detective Jennifer DiPonzio.
“At this point, I don’t know [if there’s any hope of the case being solved], I don’t know,” said Darlene McKissick, Martin’s mother, in a recent interview with ABC15. “So much has been covered up. So much has been lost. There’s been so many lies. There’s been a lot of deception.”
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Det. DiPonzio was the main case agent initially assigned to Martin’s case.
It was transferred to another detective six months later when she went on medical leave.
After Diponzio went on leave, her supervisor discovered she had at least a dozen issues that were negatively impacting the investigation, according to case inspection notes obtained by ABC15. The documented issues include a search warrant filed with incorrect information, missing search warrants, and missing reports.
Records also show DiPonzio failed to upload recordings and document interviews with key witnesses from the day of the murder.
“As a mom, it’s very hurtful,” McKissick said. “He may not have been a somebody to you. But he is a somebody to us.”
Martin’s family didn’t know about DiPonzio’s widespread investigative failures in his case until they were contacted by ABC15.
The family also didn’t know that a complaint they filed against DiPonzio in September 2021 for a lack of communication was dismissed. Her supervisor, Sgt. Jerry Barker, dismissed the complaint even though he documented widespread problems with her investigation in Martin’s case and many others.
“I knew there was some sheisty stuff going on his case because I could feel it,” McKissick said.
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DiPonzio, who’s married to an assistant chief, repeatedly mishandled evidence and failed to keep up on her cases for years.
But before the full extent of her mistakes and misconduct was discovered, she went on medical leave in July 2021.
She never returned to work and retired under a confidential disability claim.
So far, issues have impacted 37 ongoing court cases and 61 police investigations, according to police and court records.
In one first-degree murder case, a judge is holding hearings for a motion to dismiss the case for outrageous prosecutorial misconduct.
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DiPonzo’s mistakes and misconduct, including how police and prosecutors worked to obscure them, are also being raised in past convictions.
“Recently, it has come to the attention of [Randall] Barnes that there have been serious issues with Det. DiPonzio dating back to her time with the sex crimes bureau, as far back as 2013,” according to a Notice of Post-Conviction Relief filed in August. “Specifically, there have been multiple media stories exposing problems with Det. DiPonzio about which MCAO and/or Phoenix police were aware at and before the time Mr. Barnes entered his change of plea and was sentenced.”
In November 2021, Barnes was sentenced to more than 10 years in prison for manslaughter.
His notice highlighted several ABC15 reports as proof that police and prosecutors withheld key exculpatory evidence.
“Based on what is now known, the defense now possesses definitive proof that that State failed to disclose to the defense material impeachment information respecting Det. DiPonzio, the primary detective in this case,” according to the notice. “There is absolutely no question that the materials involved, and the information respecting Det. DiPonzio constituted impeachment the State was obligated to disclose pursuant to Arizona law.”
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In addition to impacting current and past court cases, DiPonzio was internally blamed in an unsolved murder. In 2020, DiPonzio interviewed a witness who identified a pair of suspects but never uploaded the recordings or documented the interviews. Another detective discovered the missing interviews after she went on leave.
“This information would have progressed the investigation that has since stalled and possibly lead to an arrest and a closure,” the memo stated.
The failure to upload and document interviews mirrors some of the same problems in Anthony Martin’s case.
When asked if she felt like the family had been misled about how the investigation was going, McKissick said, “I know we were misled.”
Phoenix police did not directly address questions asking if the department failed to properly oversee DiPonzio’s work and investigate her mistakes.
Instead, a spokesperson released the following sentence about the Martin investigation: “This is still an open and active case under investigation by the homicide unit.”
Contact ABC15 Chief Investigative Reporter at Dave@ABC15.com.
