A Colorado native with a history of violent crime and animal cruelty has been arrested in Arizona for the alleged murder of a 67-year-old man inside his Scottsdale townhome.
Victim Found Dead After Welfare Check
Police identified the victim as Frank Quaranta, who lived near 68th Street and McDowell Road. Quaranta was discovered dead inside his home on Monday, Sept. 1, after co-workers reported he failed to show up for work. Scottsdale police forced entry into the residence around 1:30 p.m. and found Quaranta’s body. Investigators described the incident as a “targeted attack.”
Suspect: Matthew Dieringer
The suspect, Matthew Dieringer, 35, was arrested Saturday following a statewide search. Scottsdale Police warned the public not to approach him, describing him as “manipulative and charismatic,” someone who often befriended others to gain shelter.
Dieringer, who has experienced homelessness, has a lengthy criminal record in both Colorado and Arizona.
Violent Past in Colorado
In 2020, Dieringer was convicted of felony aggravated animal cruelty in Teller County, Colorado, after killing and dismembering two dogs belonging to his roommate. Authorities arriving at the scene described finding walls covered in blood, holes in the structure, and what looked like evidence of the animals being slammed. The dogs’ remains were later recovered from a plastic tote and bathtub drain.
Animal Control Officer Trixie Hudspeth later called the scene “difficult” and said neighbors reported hearing Dieringer in an “enraged mental state” the night before. Dieringer received an 18-month prison sentence but was credited with 705 days of time served, meaning he was released soon after.
Arizona Arrest History
Since relocating to Arizona, Dieringer has continued to rack up charges. Court records show:
A guilty plea for theft in April 2024
Assault charges stemming from a June 2024 incident
Prior arrests for criminal mischief and burglary
Investigation Continues
Authorities have not revealed how Quaranta and Dieringer knew each other, or what may have led to the fatal encounter. Dieringer is currently being held without bond as investigators prepare formal charges.
Police say detectives and crime scene specialists spent hours processing Quaranta’s home for evidence, though no further details have been released about the cause of death.
The case has shaken the Scottsdale community, raising concerns about repeat offenders and how dangerous individuals can cycle back into neighborhoods after serving short sentences.
