SCOTTSDALE, AZ – A suspect linked to the recent killing of a Scottsdale man was arrested, bringing a tumultuous week for the local community closer to resolution.
Matthew Dieringer was taken into custody by Phoenix police on Saturday for violating the conditions of his probation. The arrest happened just days after 68-year-old Frank Quaranta was discovered dead inside his townhome near 68th Street and McDowell Road in what investigators described as a targeted assault. Police said Quaranta, who suffered evident blunt force injuries, was killed in an attack that startled neighbors and those who knew him.
Investigators revealed Dieringer had been living with Quaranta for several months prior to the homicide. According to police, Quaranta, a caring and generous figure in the community, had extended his support to Dieringer out of goodwill, a gesture authorities believe may have ultimately cost him his life.
Dieringer, who has a known history of homelessness, emerged as a suspect earlier in the week. Law enforcement described him as highly manipulative and capable of gaining the trust of others, only to take advantage of them. Officials familiar with Dieringer’s record referred to him as someone who frequently used his charm for personal gain, showing little empathy for others.
Further examination of Dieringer’s background uncovered a string of violent crimes and troubling incidents both in Arizona and Colorado. Public records detail previous felony charges, including cruelty to animals and theft. Documents also indicate an incident last summer when Dieringer allegedly attacked a stranger and then assaulted two dogs after tricking their owners.
Mental health experts describe Dieringer as impulsive and dangerous, suggesting that he seeks out shocking behavior to fulfill his own desires. Their assessment points to a lack of remorse and a pattern of escalating violence that poses a threat to those around him.
The break in the case came on September 6, when a Phoenix resident reported seeing someone matching Dieringer’s description near 13th Street and Indian School Road. Officers responded quickly, detaining Dieringer less than an hour later.
At the time of Quaranta’s death, Dieringer was on probation for theft-related offenses. Police confirmed that additional charges connected to the homicide are forthcoming, though details regarding those charges remain pending. His booking photograph was not released to the public as of Sunday.
Quaranta’s death leaves a significant void in the Scottsdale and Phoenix communities. He was a staff member at the Wesley United Methodist Church’s cooling center, where he dedicated himself to supporting unhoused residents. In the wake of his passing, church leaders announced the cooling center would close for the remainder of the year out of respect for Quaranta and the well-being of the community.
Scottsdale police praised their officers’ efforts, as well as cooperation from Phoenix police and tipsters whose information led to Dieringer’s arrest. Police Chief Joe LeDuc emphasized the collaborative approach as key to apprehending the suspect and delivering justice.
As investigators continue to review evidence, Dieringer remains in custody at the Maricopa County Jail while the prosecution weighs additional charges in connection with Quaranta’s death.