Anne Dudek’s Psych role as Lassiter’s partner, Lucinda Barry, in the pilot episode was quickly replaced by Juliet (Maggie Lawson). Starting with Psych season 1, episode 2, Juliet was the main love interest of Shawn Spencer (James Roday), one of the show’s two main protagonists. She was also partnered with Carlton Lassiter (Timothy Omundson) at the Santa Barbara police department. Juliet worked alongside Lassiter in solving homicide cases, with Shawn and Gus (Dul Hill) always getting in the way and coming to their own conclusions about each death.

https://screenrant.com/psych-anne-dudek-replaced-juliet-reason-why/