Background: Matthew Dieringer at his court appearance on Sept. 7 (KPHO). Inset: Matthew Dieringer (Scottsdale Police Department).
An Arizona man who dedicated himself to helping others allegedly died at the hands of someone who took advantage of his goodwill.
Matthew Dieringer, 35, was arrested on Saturday, days after he was named as the primary suspect in the brutal beating death of 68-year-old Frank Quaranta. In a probable cause affidavit reviewed by Law&Crime, police said that Quaranta allowed Dieringer to live in his townhouse in Scottsdale for the past three months. Quaranta met Dieringer through his church”s homeless outreach program, specifically the cooling station that he helped to run.
Police said that Quaranta’s coworkers told them that he was trying to find a way to get Dieringer to move out of his home. On Sept. 1, Quaranta was found beaten to death.
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According to the affidavit, rumors had begun to circulate that Dieringer fled Colorado after he was convicted and served prison time for killing and dismembering his roommate’s dogs in 2020. The rumors turned out to be true; Dieringer was sentenced to 18 months in prison in 2023 after being found guilty of aggravated animal cruelty.
On the morning of Sept. 1, coworkers were concerned when Quaranta did not show up for work. Police embarked on a welfare check at Quaranta’s home. When police found blood on the front door handle, they forced their way inside.
They were met with a bloody scene, and Quaranta was already dead. Police stated that he had suffered “extensive trauma to his head,” including a broken jaw and skull fractures. He also had several rib fractures, according to the medical examiner, and defensive wounds to his arms. At the scene, police saw two metal sculptures, one of which was “covered in blood.” There was also an overturned desk nearby that had blood on it, and blood was also seen splattered on the walls.
Police soon connected Dieringer to the scene after finding paperwork with his name on it in the guest bedroom. Also found in the bedroom: “a bloody shirt and blood-soaked socks in a dirty clothes bin and blood on a large pair of boots.”
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After examining Quaranta’s cellphone, police apparently found evidence of a conversation between the victim and the suspect. The two had reportedly discussed lunch plans on Aug. 31. Quaranta’s Apple Watch was also examined, and the device tracked his last “active energy” at 10:47 p.m. that night.
Police then set their sights on finding Dieringer, who allegedly violated his parole. In a Facebook post identifying Dieringer as the suspect, Scottsdale Police described him as “manipulative and charismatic, often befriending others to assist him with a place to stay.” According to local CBS affiliate KPHO, someone walking their dog in Phoenix recognized Dieringer on the morning of Sept. 6 and called police. Phoenix police responded to the scene and arrested Dieringer.
While in custody, Dieringer was reportedly less than cooperative. According to the affidavit, Dieringer refused to comply with a search warrant for his DNA. Police said he had to be “secured in a chair” in order to have his blood drawn. While in custody, police noticed several fresh injuries on Dieringer, including abrasions to his hands and ankles.
Police stated that DNA found on the bloody socks and shirt found at the scene matched Quaranta’s. Dieringer’s DNA was also found to match another blood found on the same items.
Dieringer was charged with first-degree murder and made his first appearance in court on Sunday. According to KPHO, Dieringer claimed to the judge, “I believe that you are being given wrong information about me entirely, and my name, and that these proceedings are illegal and there’s no truth to what that woman or that system is giving you.”
Dieringer is being held on $2 million cash bond. He has a status conference scheduled for Friday.
