Contains spoilers for “S.W.A.T.” Season 8, Episodes 17 — “The Enemy Within”

When 40 Squad needs a criminal profiler, there’s only one woman they turn to — LAPD shrink Dr. Wendy Hughes (Cathy Cahlin Ryan). Hughes has appeared 15 times on the drama during each of its eight seasons, but this time the episode’s plot revolves around her. A vital part of 40 Squad’s latest case, she’s been treating three cops who all become victims of a sniper. The other common thread that connects them? They were a part of the infamous, squad-traumatizing failure of the thankfully not-based-on-a-true-story De La Costa High School mass shooting.

Wendy puts herself in the line of fire by willingly making contact with the perp, Claude Fournier (Richard Ellis). Fournier is a former cop himself, and is furious with Wendy for helping to push him out of the force by noting in a profile that he only joined up because policing is a family tradition. That, plus his guilt over his own involvement in the De La Costa High School incident, put his life — and Wendy’s — in major jeopardy. Fortunately, Hondo (Shemar Moore) is on the scene and willing to help.

Procedural fans will always remember Cahlin Ryan as Corrine Mackey, the long-suffering estranged wife of Vic (Michael Chiklis), who decides to suffer no more in the near-perfect action show “The Shield.” But there’s a lot more to her than her cop show roots. Here’s why she might look familiar to you.

Cathy Cahlin Ryan started acting in a pretty prestigious place, with an uncredited appearance as a dippy hippie in the Season 3 “Seinfeld” episode “The Keys.” She landed her role on “The Shield” in 2002, but during its long run she guest-starred on numerous other shows, including “The Unit,” “Monk,” and “Judging Amy,” in which she played a member of a child-smuggling ring. When “The Shield” wrapped in 2008, she appeared in the bloody martial arts and crime film “Redbelt.” 

She also popped up in the series “N3mbrs,” played Beth in “Lie to Me,” and had small roles in “Justified” and “The Chicago Code.” Cahlin Ryan is an accomplished short film writer, and has also starred in film versions of her own scripts, including “The Bath.” But she admitted to The Mighty that playing Wendy so frequently has had a great impact on her life. “I love playing Dr. Wendy,” she said. “I really enjoy it and I think the biggest thing is the listening … I try not to, even with my family, get emotional right away, but try to read them myself and have more reasonable awareness. It has had, in my opinion, a positive effect on me and I just love it.” Here’s hoping that she manages to make one more appearance on the show before “S.W.A.T.” closes up shop for good this May.