A 35-year-old homeless man with a disturbing criminal history has been arrested in Arizona for the murder of a 67-year-old man inside his Scottsdale townhome. The case has raised alarm in the local community, especially due to the suspect’s past behavior and violent record.
Who Are the Victim and the Accused?
The victim, Frank Quaranta, 67, was found dead inside his home near 68th Street and McDowell Road in Scottsdale, Arizona. He had failed to show up for work on September 1, prompting a welfare check.
When police arrived at his house around 1:30 p.m., they couldn’t reach him and had to force their way inside—only to find him dead.
The suspect, Matthew Dieringer, is a 35-year-old man originally from Colorado. Known to be homeless and described by police as “manipulative” and “charismatic,” he has a long criminal history in both Colorado and Arizona. He was arrested the following Saturday and is currently being held without bond.
A “Targeted Attack” in a Safe Neighborhood
Scottsdale Police described the killing as a targeted attack, though the exact relationship between Quaranta and Dieringer is still unclear. The investigation began immediately after Quaranta’s body was discovered. Detectives and crime scene experts spent hours collecting evidence from the home, trying to piece together what happened.
Dieringer’s Shocking Criminal History
Matthew Dieringer is no stranger to law enforcement. In 2020, he was convicted of felony aggravated animal cruelty after killing and dismembering two dogs that belonged to his roommate in Colorado. The crime scene was described as horrific:
Blood on the walls
Evidence of a violent struggle
Dog remains found in a plastic tote and bathtub drain
Neighbors in Colorado had reported Dieringer acting aggressively and shouting the night before the incident. He was sentenced to 18 months in prison but got credit for 705 days already served.
Since then, Dieringer moved to Arizona, where he continued to face multiple charges, including:
Theft (pleaded guilty in April 2024)
Assault (charges from June 2024)
Burglary and criminal mischief (prior incidents)
This pattern of violent and erratic behavior has raised serious concerns about how someone with such a history remained free.
Police Warnings and Arrest
Before his arrest, Scottsdale Police had issued a public warning about Dieringer, describing him as potentially dangerous and advising people not to approach him. Authorities stressed his ability to be charming and manipulative—often making friends just to get shelter or support.
Thankfully, Dieringer was arrested without further incident, and he now awaits formal charges for Quaranta’s death.
What Happens Next?
As of now, police haven’t released specific details about what charges Dieringer will face in relation to Quaranta’s murder. But given his violent past and current accusations, it’s expected that the legal process will be intense and highly watched.
The investigation is ongoing, and detectives are likely looking into how Dieringer and Quaranta met, and what led to the deadly attack.
This tragic incident highlights how individuals with serious criminal backgrounds can still pose a threat to society if not properly monitored.
The loss of Frank Quaranta has left a community mourning, and the case has once again brought attention to the gaps in tracking repeat offenders—especially those struggling with homelessness and mental health issues. As justice takes its course, many are left asking how such a crime could have been prevented.
