According to Dr. Marc A. Kates, Farina had been in treatment for lung cancer for several months. The doctor said Farina had been diagnosed with "a small cancer that was treated and cured with surgery" 13 years ago.
But the cancer recurred in recent months. Despite ongoing treatment, the doctor said that blood clot "unexpectedly and suddenly took his life." The former cop turned actor died in a Scottsdale, Ariz., hospital.
Farina, known for his role as Det. Joe Fontana in "Law & Order," spent 18 years with the Chicago Police Department. He started acting as a sideline and landed his first role in the 1981 film, "Thief." In 1986, he took a leave of absence from his law enforcement career to star in a TV series.
Farina's work on "Crime Story" convinced him it was time to hang up his badge and give acting a go full-time.
Farina is survived by three sons, six grandchildren and his longtime partner, Marianne Cahill.
The Associated Press contributed to this report.