Main Character: New York
Name Donald Flack
Gender Male
Birth Date 1978
Family Irene Flack (grandmother)
Donald Flack, Sr. (father; deceased)
Samantha Flack (sister)
Jessica Angell (girlfriend; deceased)
Jamie Lovato (girlfriend)
City New York
Job Homicide Detective
Rank Detective 1st Grade
Status Alive
Portrayed By Eddie Cahill
First Appearance Blink

Detective Donald "Don" Flack, Jr. is a detective that works closely with the CSI team on CSI: NY. Unlike the other detectives in the NY Crimelab, Flack is not a certified CSI.


Flack comes from a long line of law enforcement officials. He bridges the gap between old-school NYPD and the new generation of CSI. He is a witty detective who has very little patience for the "bad guy", and his techniques are sometimes considered borderline, though effective. He is good friends with Danny Messer, and is always willing to lend an ear to Danny's problems.

Flack can be said to be "hardcore," and "two-faced." While he is typically a humorous, nice, and caring guy... he can also be tough, moody, and very intense at times. When interrogating suspects, his temper is very short; and he often "goes off" on them, sometimes with substantial intimidation (including yelling and screaming at them, as well as occasional physical gestures). He also often directly comments on their bad behavior, saying how wrong and unacceptable it is, sometimes in a humorous way. While he often plays the role of "bad cop" in interrogation, he does not physically assault suspects. However, he also has a kind, soft side, which he often shows to other workers in the lab. He also cares for, and deeply sympathizes with those who are victims of crimes, saying how much he understands their feelings. He's also protective of those who have been wronged.


Detective Flack is portrayed as the legal muscle for the CSI: NY team. He often plays the role of the "tough, hardcore" guy who does what he can to bring criminals to justice, and to get the answers the CSIs are looking for. He can often be seen interrogating suspects with a characteristic wit and sarcasm. Though not as highly educated as the CSIs (He only has a high school diploma, and is not seen working in the science labs), Flack is intellectual and trusts CSIs' judgment and respects their findings. He also has skill in working with a variety of different kinds of people hands-on. Throughout the series, he defends them to skeptical colleagues, especially in "Raising Shane." In "Zoo York" it is revealed he is allergic to cats (which is again mentioned in "Turbulence").

In "Communication Breakdown," he revealed being taught some Irish by his grandfather and that he can effect an Irish accent. The extent of his fluency is not fully known, however he is able to translate some Irish in Sláinte.


Flack is a homicide detective with the NYPD, known for both his dry wit and his determination to hunt down suspects (even to the point of chasing them down alleys and over rooftops). He was mentored by another cop, Gavin Moran, whom he is later forced to arrest after it comes to light that Moran concealed evidence during the course of an investigation ("The Fall"). He is at least a second-generation cop; Moran mentioned having worked with Don, Sr. as well. He is both a colleague and a friend to the members of the New York Crime Lab. After Stella Bonasera is attacked in her apartment by her unstable boyfriend, Flack gently helps her through when he comes to the hospital to take her statement ("All Access"). His friendship with Mac Taylor is tested when Taylor uncovers evidence that one of Flack's men is a dirty cop and asks Don to turn over his memo notebook to prove it. Though Flack eventually capitulates, their relationship is a bit tense for a some time after ("Consequences" and "Sweet 16"). Flack defends Taylor to Captain Gerrard, who is investigating Sheldon Hawkes, the prime suspect in a robbery-homicide, after Taylor locks himself in the interrogation room with Sheldon. Flack affirms that Gerrard would do the same for him (Flack) ("Raising Shane"). He is also close to Danny Messer, attempting to offer him some sound advice in "On the Job" when it appears that Danny accidentally kills an undercover officer. It is also assumed that Danny and Flack spend some of their downtime together as friends; in the very first episode "Blink," Danny is exiting an interrogation room and casually says to Don "Hoops on Saturday, Flack. Don't forget." They are seen together at a basketball game in season 4. They also meet up for drinks and pool in "...Comes Around," and have a heart-to-heart talk about their jobs and why they do what they do.

Mutual interest between Flack and Detective Jessica Angell has been hinted at in several episodes; first in "Commuted Sentences." This was finally proven when they locked lips at the end of season 5, "Dead Inside". In "Rush to Judgement," the professionalism of their relationship was questioned while Flack was under investigation by Internal Affairs. They kept it quiet but revealed to the viewers they were indeed "seeing each other." This ended when Angell died during the season 5 finale "Pay Up," after suffering injuries during a shootout. A grief-stricken and enraged Flack eventually tracked down her killer during a bust, cornering him and killing him point-blank.

In the premiere episode of season 5, "Veritas," Don's sister, Samantha Flack, was introduced: Samantha's car was caught on a toll booth camera being driven by bank robber Joe. As Samantha is slated to be a recurring character, there will be an ongoing storyline more focused on Flack's personal life. One part of the storyline, started in the episode "Dead Inside," was Flack's discovery that his sister is an alcoholic who went to a recovery support group (unknowingly followed by Flack).

Season Two[]

While Flack is not seen working as many late night hours as Mac, he shows determination in a different way- through intensity, sometimes extreme, to get the job done.

In Charge of this Post, Flack is critically injured when a bomb goes off in a building he and Mac are evacuating. Until their rescue, Taylor is able to keep Flack alive using a shoelace and from prior experience in the Beirut barracks bombing. Flack remains unconscious for the remainder of the episode, but has since fully recovered, his concerned colleagues (especially Mac) keeping vigil at his bedside.

Season Three[]

When Flack returns to work, his friends tease him about using his "battle wounds" to impress the ladies ("People With Money").

Later, Flack is instrumental in the safe resolution of a crisis when he and another officer successfully rescue the infant daughter of an angry and upset young deaf man holding both the baby and his dead girlfriend's mother hostage. While Mac Taylor distracts the man on one side of the car, Flack and the other officer sneak up on the other and take the child out through the window, whereupon Taylor is able to safely disarm the man. Flack then returns the baby to the care of her relieved maternal grandparents ("Silent Night").

When the aforementioned arrest of Flack's subordinate results in the release of a serial killer, Flack berates Mac, who angrily counters that they both want the man back behind bars. They put aside their indignation to collar the murderer once more. Flack is mere feet away when the man plummets from a roof, handcuffed, and lands on a police cruiser, fatally wounded. Looking up, he sees Mac staring down at him from where the suspect fell ("Past Imperfect").

As a child, Flack would sometimes play in a hedge maze in Queens, where he later investigates the death of a Chelsea University student, though he says that, by that time, he hadn't been there in years ("Some Buried Bones").

Season Four[]

His family, which includes a sister named Samantha and at least one brother, lived in Queens, and his mother used to make corned beef every Wednesday, which Flack later terms "paradise." Flack claims that he would "endure every one of [his] brothers' insults for one more taste of that paradise" ("Time's Up"). He also says that he "was a Monopoly guy," (in response to a comment Stella Bonasera made regarding the board game Clue in "Trapped"). Flack appears to have an appreciation for fine wine, instantly realizing the value of the bottles in a murdered chef's private cellar in "A Daze Of Wine And Roaches."

Season Five[]

In the season 5 episode Rush to Judgement, Flack comes under heavy investigation when a suspect dies in his custody during an interrogation. His badge is revoked and he is demoted to desk duty until the end of the episode, in which his name is cleared. During the investigation, the team is shown to support him, with Stella Bonasera saying that "[Flack] does everything by the book," and showing up to offer words of comfort to Flack while he's working.

In the Season 5 finale Pay Up, when Jessica was on escort duty for Conner Dunbrook, who is testifying against his father for a lighter sentence, a Hummer rams through the window of the cafe they were eating at and Jess is shot while Conner is kidnapped. Despite Flack's best efforts, Jess dies in surgery, devastating him. He continues working the case until they manage to rescue Conner from the kidnappers and Flack himself confronts Jess' killer, Simon Cade. Finding a Desert Eagle nearby, which was the gun that killed his girlfriend, Flack chooses to avenge Jess by executing Cade instead of arresting him.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 #
Season 1 X X X X X X X X X X X X X X X X X X X X X X X N/A 23
Season 2 X X X X X X X X X X X X X X X X X X X X X X X X N/A 24
Season 3 X X X X X X X X X X X X X X X X X X X X X X X X N/A 24
Season 4 X X X X X X X X X X X X X X X X X X X X X N/A 21
Season 5 X X X X X X X X X X X X X X X X X X X X X X X X X 25
Season 6 X X X X X X X X X X X X X X X X X X X X X X X N/A 23
Season 7 X X X X X X X X X X X X X X X X X X X X X X N/A 22
Season 8 X X X X X X X X X X X X X X X X X X N/A 18
Season 9 X X X X X X X X X X X X X X X X X N/A 17
Total 197


Flack: I can't believe how crowded this city's gotten. You can't even dump a body in private anymore.
Flack: I'll start with the nuts in this city, and work my way up.
Flack: A couple of kids came into the 3-5, said that a friend's football may've accidentally killed a man. I locked them up for fun.
Flack: 'I've slept with a lot of women. Some wild, some crazy, some both.' -Quoting someone else
Flack: Lemme arrest him for swearing on his grandmother. - To Mac
Flack: That guy's a few chicken nuggets short of a Happy Meal.


  • Flack claims not to use the bathroom in public. (Tri-Borough)
  • Flack stated that his first words said when he was a child are "Cookie" and "Cake". (Do Not Pass Go)
  • Flack is a fan of the New York Jets (Near Death) and the New York Yankees (2,918 Miles).
  • Flack has a cousin who had a job where he handled birds. (The Lady in the Lake)
  • Flack is left-handed and wears his watch on his right hand.
  • Flack is allergic to cats.
  • He usually uses a Glock 19 as his weapon of choice but is sometimes seen with a stainless SIG Sauer P226.