He can be briefly seen during the opening cutscene of the Strangers and Freaks mission, "Unknowing the Truth". Joscha can also be seen at the Epsilon Building, along with Ameer, Haylee, Jesse and Tiana, the other four people that the Cultstoppers believe to be kidnapped.
Joscha's character model is available in the Director Mode, under the Gangs section as an Epsilonist, also along with the other four people.
Grand Theft Auto V
Between 29th of April, and 27th of May 2013, anyone could apply to be cast as one of the five Epsilon characters. Joscha was one of the fans selected from the Epsilon Casting Event and is therefore modeled on the likeness of Joscha. .