Inset: Matthew Dieringer (Scottsdale Police Department). The townhome complex where Matthew Dieringer allegedly killed 67-year-old Frank Quaranta in Scottsdale, Ariz., last week (AZFamily/YouTube).
Police in Arizona have arrested a “manipulative” and “charismatic” homeless man known for “befriending others” in connection with the alleged murder of a 67-year-old man inside his Scottsdale townhome.
Matthew Dieringer, 35, is charged with killing Frank Quaranta — a resident near 68th Street and McDowell Road — in what authorities describe as a “targeted attack.” The incident came to light on Monday afternoon when a welfare check was conducted after Quaranta missed work, as stated by the Scottsdale Police Department.
Dieringer, originally from Colorado, was found guilty in 2020 for the assault and dismemberment of his roommate’s two dogs. He served 705 days of an 18-month prison sentence before moving to Arizona, according to court documents.
“He has experienced homelessness and is characterized as manipulative and charismatic, often befriending others to secure a place to stay,” said SPD officials in a Friday press release while announcing his arrest on Saturday. Authorities advised, “If Dieringer is seen, exercise caution and do not approach; contact 911 immediately.”
Police say Quaranta was killed last Monday, Sept. 1, inside his home. It’s unclear how he and Dieringer allegedly met.
“The call for the welfare check reached Scottsdale PD at around 1:30 p.m. on September 1, after the victim failed to go to work,” officials from SPD noted. “Officers who responded could not reach the victim via other means and forced their way into the residence to check on Quaranta. Unfortunately, Quaranta was found dead inside. Detectives and crime scene teams spent several hours collecting evidence from the scene.”
Court records show Dieringer has had multiple run-ins with the law in both Arizona and Colorado, with a recent guilty plea being entered for theft in April and charges for assault stemming from a June 2024 incident. He also has prior arrests for criminal mischief and burglary.
In 2020, Dieringer killed and dismembered two dogs belonging to a roommate of his in Teller County, Colorado, with cops entering their residence to find the walls covered in blood and evidence of a struggle, including multiple holes and a blood spatter spot that looked like Dieringer was slamming the animals, according to local ABC affiliate KRDO.
“The scene we went into was difficult,” said Trixie Hudspeth, Teller County Sheriff’s Office Animal Control Officer, in a statement to the outlet.
According to KRDO, neighbors reported hearing yelling and seeing Dieringer in an “enraged mental state” on the night before authorities arrived at the home. The dogs’ remains were found in a plastic tote and bathtub drain, including tooth fragments and dog hair.
Dieringer later pleaded guilty to felony aggravated animal cruelty. He was being held without bond over the weekend for Quaranta’s death. Cops have not released information on what charges he is facing.
