Stand in for Frank Holloway in a few episodes of the third season. At first Rachel Goldstein and Jack hate each other (read: Rachel hates Jack), but after some time things seems to change a bit between the to detectives.
Jack assigns to the Water Police and becomes Rachel Goldstein's partner after Frank Holloway leaves.

Season 3 (1998) - present
(first appearance in episode 56 "One for the social workers")