Mark-Paul Gosselaar

Mark-Paul Gosselaar will guest-star in an upcoming episode of the new TNT drama Rizzoli & Isles, TVGuide.com has learned exclusively.

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Gosselaar will play Garrett Fairfield, an old college boyfriend of medical examiner Maura Isles (Sasha Alexander), in the sixth episode of the show's first season. Garrett, a member of one of Boston's oldest, wealthiest families with roots that trace back to the landing of the Mayflower, returns to Boston to mourn the death of his older brother.

Homicide detective Jane Rizzoli (Angie Harmon) investigates Garrett's brother's murder, but becomes distracted by news of Isles' own wealthy background.

Check out photos of Gosselaar through his career

Gosselaar, who rose to fame playing high school heartthrob Zack Morris on teen sitcom Saved By the Bell and most recently starred in TNT's Raising the Bar, is keeping busy these days. Earlier this week, he signed on to guest-star on the upcoming sixth season of Weeds. He will also return to TNT next year in the legal drama Franklin & Bash, alongside Breckin Meyer and Malcolm McDowell.

The 36-year-old actor's personal life isn't as cheery: Gosselaar, who separated from his wife of 14 years earlier this month, filed for divorce on June 18, citing irreconcilable differences, according to People.

Rizzoli & Isles premieres Monday, July 12 at 10/9c on TNT.