One of the biggest questions on the public's mind after Tuesday night's fatal stabbing spree: why? Investigators are working to determine exactly what caused 28-year-old Arthur DaRosa to stab four people, killing two, and assaulting three others in two locations in Taunton Tuesday night. "It's unclear," says Bristol County District Attorney Thomas Quinn III. "This appears to be an irrational series of actions. But we're going to continue to investigate. It's difficult to comprehend what this man did without, what appears at this point, any rational motive."

Quinn says in an interview with DaRosa's sister, she revealed that she had her brother was acting in a "disturbed manner" Monday, making "irrational statements." DaRosa's sister encouraged him to seek help. DaRosa checked himself into Morton Hospital Monday afternoon, only to be released Tuesday morning.

He was attending his child's soccer practice Tuesday at about 6 p.m. when he left the field without clear reason, driving a vehicle belonging to his child's mother down Myricks Street when he struck a parked truck. After the accident, DaRosa went to several homes in that neighborhood, attempting to gain access into the residences.

He was able to enter the home of 80-year-old Patricia Slavin at 270 Myricks St. Slavin was having dinner with her daughter, 48-year-old Kathleen Slavin, when DaRosa burst into the home and stabbed both women with a knife. Both women were transported to Morton Hospital where Patricia Slavin was pronounced dead. Kathleen remains in the intensive care unit and is in stable condition.

After DaRosa left the Slavin home, he attempted to carjack several passing vehicles, ultimately resorting to driving the damaged car he arrived in, and drove to the Silver City Galleria Mall.

DaRosa drove the 2010 black Honda Accord through the entrance of Macy's department store at the Silver City Galleria, entered the store, and proceeded to assault three women before making his way to Bertucci's Italian Restaurant in the mall. Those women were transported to Morton Hospital. Two of them have been released.

Upon entering Bertucci's, DaRosa was approached by several staff members looking to assist him before he grabbed hold of a nearby knife and repeatedly stabbed 26-year-old Sheenah Savoy, a waitress at the restaurant. 56-year-old George Heath was dining with his wife when he saw DaRosa attack the waitress. Heath and his wife attempted to stop DaRosa, who turned his knife toward the teacher, fatally stabbing him in the head.

Off-duty Plymouth County Sheriff's Deputy James Creed was also dining with his wife in Bertucci's when DaRosa carried out his attacks. Creed displayed his badge and his gun, commanding DaRosa to drop the knife. When DaRosa continued his assaults, Creed fired one shot into DaRosa's abdomen. DaRosa was transported to Morton Hospital where he was pronounced dead.

District Attorney Quinn says Tuesday's events remain under investigation.