Frank Barlow is a Caucasian detective in the homicide unit who first appeared as the primary detective at the trial of D'Angelo Barksdale. Despite having two witnesses, Barksdale is found not guilty due to witness intimidation in the court room.
Barlow appears later in the series with open murders of homeless men that his colleague Jimmy McNulty ties into his fabricated serial killer. Barlow then sees that McNulty is falsifying paper work on the homeless murders case to provide resources for detectives to investigate unrelated cases. Barlow blackmails McNulty into providing funds for him to take a long weekend to play golf in South Carolina.