First Grade Detective Don Flack knows the streets of New York. Yankers bred, a long line of police officers. Flack's future was never in the question working close to Mac Taylor, and his unit.

Detective Flack bridges the gap between the old school NYPD, and the new generation of CSI! Det. Flack doesn't stray away from confraction, but he does stand up for the people he works with on a daily basis.

All CSI NY fans found out in "You Only Die Once" that Detective Flack does charity work and that is how he met his girlfriend. We also learn in that same episode that the NYPD has a policy against high speed prusits. For his effort to try to apprehend the burglar, he gets a grilling from Chief Sinclair.