A 21-year-old man has been arrested on suspicion of stabbing his parents and grandmother earlier this month, authorities say.
Thomas O'brien faces three counts of aggravated assault for the May 9 incident, according to the Marana Police Department.
No motive for the attack was given.
Police initially received reports of a physical domestic violence incident in which O'brien allegedly cut his father with a knife. Β Officers arrived on scene to find that O'brien's mother and grandmother as well.
All three people were hospitalized. The father suffered life-threatening injuries, but has since been released from the hospital, police said.
O'brien was booked into the Pima County jail.
