Greco-Italian Stella Bonasera is a Detective First Grade and CSI with the NYPD. Born in Greece, Stella was brought to New York at the age of two by her artist mother. After her mother was killed in a car accident, Stella was raised in St. Basil's Orphanage and in a variety of foster homes. Though lonely, she maintains some good memories of her childhood: a particularly loving foster mother and foster sister, and the dance lessons that continued through her youth.
Tough and by-the-book, Stella has an impressive track record of arrests and convictions, but also four complaints on her jacket, which she dismisses as spurious. Her legalistic mind allows little gray area in cases, until she is forced to fight for her life. This alters her reaction to cases involving abused women, and even causes her to give her now-adult foster sister a day's grace to disappear instead of arresting her for the murder of their sexually abusive ex-foster father.
Stella has a close relationship with her CSI parter, Lab Supervisor Mac Taylor, with whom she shares a deep trust and respect based on endless hours of work, and literally saving one another's lives over the years. In early scenes, Mac tells her that "he wouldn't do the job without her". Though the two challenge and provoke one another over the years, they remain steadfast partners, sometimes seeming to speculate individually on a deeper relationship, but never crossing the line.
Directing her love of family toward her colleagues, Stella is the unofficial mother of the CSI team. She mentors them professionally and assists them personally when she can, and is seen being exceptionally gentle with small children involved in cases. She observes her chosen family closely, sometimes dropping highly perceptive comments about their motivations and habits. While she sometimes dates casually, her two recent relationships ended so disastrously - being forced to shoot one ex boyfriend in self-defense, and then finding herself the pawn of her next boyfriend's sadistic revenge plan - she appears to prefer to remain safely alone.
Stella was caught up in an international forgery operation involving her old Greek mentor, which saw her leave her badge and gun at home to continue her investigation in Greece. Knowing she was in trouble, both personally and legally, Mac followed her to the Islands, and helped her begin to find closure both with the case and with her own history. Upon returning home, she humourously "reads" Mac's Greek coffee grounds (the practice of tasseomancy, or kafemandeia in Greek), and describes herself in a thinly-veiled reference as "a woman in his life...someone he adores, even though she sometimes drives him crazy."
Stella left New York in the summer of 2010, after being offered a Supervisor position at the New Orleans Forensic Lab.