Tamaro developed the series, based on Tess Gerritsen's novels in 2010, but has decided to cede her producing and showrunning responsibilities to focus on new projects. She will remain on the TNT drama as a consultant.
"This is what we all dream of getting to do," Tamaro said in a statement. "And I got to do it for four phenomenal seasons. I'm at the top of my game, thanks in large part, to this unbelievable experience and show. It's time to challenge myself and develop new projects. TNT and Warner Horizon have been a dream to work with, and I look forward to doing it again. The heartache for me will be leaving the day-to-day working relationship with an incredible cast and crew."
Tamaro's decision comes only a few weeks after production on Rizzoli & Isles was shut down following the suicide of co-star Lee Thompson Young. Rizzoli & Isles was renewed for a fifth season in August.