1. Al Giardello is based on Baltimore Police Department Shift Lieutenant Gary D'Addario, a member of the BPD homicide unit described in David Simon's book Homicide: A Year on the Killing Streets which served as the inspiration for the series as a whole.
Al Giardello is introduced early in the series as a widower of mixed Sicilian American and African American heritage.
Al Giardello played three sports and was Prom King when he was in high school.
Al Giardello takes a degree of pride in both heritages, speaking near fluent Italian and fraternizing with many of the BPD's African American and Italian American officers alike.
Al Giardello has a particular fondness for children, manifesting itself in marked outrage whenever children are murdered, an attribute shared by many other detectives.
Al Giardello has one grandchild, Al, who was born to Charisse in January 1999.
Al Giardello expresses missing his late wife in several episodes of the first four seasons as well as his devoted, if on occasion strained, relationship with his children.
Al Giardello is only rarely given to physical outbursts of rage, such as sweeping everything off his desk or attacking a storage cabinet with a baseball bat.
Al Giardello possesses an intense belief in loyalty among fellow police officers as a "brotherhood"; in the episode "Black and Blue", he disagreed with Detective Frank Pembleton's suspicion that a cop had committed a shooting, and implied that loyalty to other cops is above loyalty to the citizenry, including the African-American citizenry.
Al Giardello tends to allow his detectives to investigate murders in a manner that is more efficient but less discreet, very much unlike the preferred methods instructed by the department's upper command.
Al Giardello is considered a renegade commander and a thorn in the bosses' side due to his tendency to alert the media about investigations and allow his officers to investigate in a way that, while effective, is not representative of the department's political objectives.
Early in the series, Al Giardello finds conflict with George Barnfather, a college-educated bureaucrat who is less experienced on the street and more interested in appeasing those who outrank him.
Al Giardello is particularly incensed when Barnfather refuses to grant Steve Crosetti an honor guard because his suicide would create bad publicity for the department.
Al Giardello joined the BPD in 1968 during a racially turbulent era and was subject to working under a predominantly White department in a largely African American city.
Gee experienced racism first-hand at the orders of his training officer Mickey Shea, an Irish officer who had forced a young Al Giardello to ride in the back of the patrol car.
Normally this would indicate that they both made lieutenant before him, but given Al Giardello's known predilection of being impolitic with the brass and Harris and Barnfather being known political animals that would play ball with their superiors, it is of strong consideration that Al Giardello was passed over for Captain by both for that reason and not strictly racism by either whites or lighter skinned blacks.
Barnfather's youth is another indicator that Al Giardello was passed over by the Bosses for not cooperating in a political manner.
Al Giardello is rushed to the hospital for emergency surgery, during which the assailant breaks in and shoots him again, as well as one of the surgeons operating on him.
Al Giardello survives the surgery and talks with his son Mike, but later dies of an aneurysm.