Veteran “CSI: NY” and “Forrest Gump” actor Gary Sinise is joining the cast of “13 Reasons Why” for its fourth and final season.

Sinise will play Dr. Robert Ellman in the Netflix YA drama. Season 4 is currently in production and will feature the core cast’s graduation from Liberty High.

Dr. Ellman is described as a compassionate, incisive, no-nonsense adolescent and family therapist who works to help Clay Jensen (Dylan Minnette) battle anxiety, depression, and grief. Ellman helps guide Clay to accept the help he needs and come to terms with the trauma in his past.

Season 3, which was released back in August, picks up eight months after the events of the previous season and focuses on Clay, Tony (Christian Navarro), Jessica (Alisha Boe), Alex (Miles Heizer), Justin (Brandon Flynn), and Zach (Ross Butler)who find ways to shoulder the burden of the cover-up of Tyler’s (Devin Druid) attempted massacre at the Spring Fling, while helping him move toward recovery.

The series also stars Timothy Granaderos, Anne Winters, Steven Weber, Brenda Strong. Amy Hargreaves, and Grace Saif. Brian Yorkey created the series and serves as showrunner and executive produce alongside Mandy Teefey, Kristel Laiblin, Selena Gomez, and Joy Gorman. The series is produced by Paramount Television and Anonymous Content for Netflix.

Season 1 was based on the novel of the same name by Jay Asher, while subsequent seasons have been original stories. The show’s freshman season was highly controversial due to its depictions of teen suicide. It was announced two weeks ago that Netflix had edited the scene in Season 1 in which Hannah (Katherine Langford) commits suicide. The scene now shows Hannah staring at her own reflection in the mirror before cutting to her parents’ reaction in a later scene, omitting the graphic depiction of her death.

Sinise is repped by CAA and Brillstein Entertainment Partners.