Cranston, who played Mitte’s father Walter White on the show, took to Instagram Monday evening to express his pain over the tragic loss, as did fellow castmates Aaron Paul and Dean Norris.

Bryan Cranston is in “deep despair” following the death of his on-screen son, RJ, Mitte, who died by suicide on Monday at the age of 34.

Mitte, who lived with cerebral palsy, drew on his own experience for his role in the Emmy-winning drama series starring Bryan Cranston.