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 being identified as the main suspect in the violent death of 68-year-old Frank Quaranta. According to a probable cause affidavit examined by Law&Crime, police reported that Quaranta had allowed Dieringer to stay in his Scottsdale townhouse for three months. Quaranta had met Dieringer through his church’s homeless outreach program, particularly at the cooling station he assisted in managing.
Police indicated that Quaranta’s colleagues informed them he was seeking a way to have Dieringer vacate his home. On Sept. 1, Quaranta was discovered beaten to death.
The affidavit mentioned circulating rumors that Dieringer had escaped from Colorado after serving time for killing and dismembering his roommate’s dogs in 2020. These rumors proved to be accurate; in 2023, Dieringer was sentenced to 18 months in prison after being convicted of aggravated animal cruelty.
Coworkers became concerned on the morning of Sept. 1, when Quaranta failed to appear at work. Police initiated a welfare check at his residence. Upon discovering blood on the front door handle, they forced entry into the home.
Inside, they encountered a gruesome scene, with Quaranta already deceased. Police reported he had suffered “extensive trauma to his head,” including a broken jaw and skull fractures. He also had multiple rib fractures and defensive wounds on his arms, according to the medical examiner. At the scene, police found two metal sculptures, one “covered in blood.” Nearby was an overturned desk with blood on it, and blood splatter on the walls.
Police quickly connected Dieringer to the scene, locating paperwork with his name in the guest bedroom. Within the bedroom, they also discovered “a bloody shirt and blood-soaked socks in a dirty clothes bin and blood on a large pair of boots.”
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.
