Played by Kim Delaney: Diane comes from an extremely dysfunctional family, and that warped upbringing, along with too many years spent working as an undercover cop, led to a lot of screwed up values on her part and may have caused her drinking problem. While working a case in tandem with Bobby Simone, they realized an attraction for one another and became lovers - a situation that became complicated when she got transferred to the 15th squad. Bobby broke up with her after realizing the extent of her alcoholism. After she spent several months in AA, she and Bobby resumed their romance, but roadblocks keep cropping up, particularly the emotional whallop Diane received after her mother shot and killed her abusive father. She and Bobby conceived a child, but she miscarried. After a few months to recover from yet another emotional setback, Diane finally married Bobby, only to get the biggest one yet when Bobby died mere months later. Diane has returned to work, but that proved to be a mistake. A lengthy flirtation and brief romance with Danny Sorenson was a disaster -- she wasn't ready to see any man, much less the one who replaced Bobby in the squad -- and after struggling to deal with guilt over "cheating" on Bobby, she decided to take a leave of absence from the department to work out her personal issues. When she returned to active duty, it was with the NYPD's Special Victims (or sex crimes) unit.
Hoping to branch out, Delaney joined the cast of "All My Children" as popular teenage character Jenny Gardner, a character she played for three seasons before leaving to try her hand at movies.
After a string of duds like "Campus Man" and "That Was Then...This is Now," Delaney high-tailed it back to the small screen, where a guest spot on "L.A. Law" (as an ambitious associate who bed Arnie Becker in order to research her novel on high-powered law firms) turned heads and got her a part on the CBS Vietnam series "Tour of Duty." Because "Tour" was airing at roughly the same time as ABC's "China Beach," Kim is often confused with "Beach" star Dana Delany, even though the two have different names and very different appearances.
Delaney took some time off from her career to give birth to her son Jack (son of her second husband, actor Joe Cortese), then settled into a niche as a TV-movie actress, before getting cast for a four-episode stint on "NYPD Blue" as a possible love interest for Bobby Simone. Her portrayal of alcoholic detective Diane Russell was good enough and popular enough to earn her a regular role on the show, and earned her an Emmy, to boot.
The problem was, so long as Dennis Franz was around, Kim was never going to get the proper showcase that "Blue" producer Steven Bochco felt she deserved, so he created a show just for her: "Philly," a legal drama that unfortunately lasted only a season. Rather than take a step back in her career and return to "Blue," Kim moved on to a role on CBS' "CSI: Miami." This didn't last long, as producers realized she was miscast and dropped her after half a season. Kim has come back to "Blue" a couple of times since then, and also starred in the miniseries "10.5."