Escalating violence is omnipresent in South African townships and can be traced back to two core mechanisms: a trauma-related hyper-arousal and a positive rewarding perception of violence. In the past, there was no therapeutic intervention available addressing both, trauma and the so-called appetitive aggression. The University of Konstanz has developed a culturally sensitive and scientifically based short-term intervention for the treatment of traumatized patients, the Narrative Exposure Therapy (NET), that has proven its effectiveness in various randomized clinical studies in different war-affected populations. Recently, the NET has been adapted for the forensic offender rehabilitation (FORNET) by also addressing the perpetration of violence related to a self-rewarding perception of the exposure with violence. It has shown to be effective in reducing the number of committed offenses in a perpetrator sample in Burundi and to reduce PTSD symptoms in a perpetrator sample in the Democratic Republic of the Congo. In this study, we investigated the therapeutic efficiency of FORNET in a randomized clinical control trial with a sample of former offenders of the townships of Cape Town. In addition to the previous studies, we specifically addressed the context of ongoing stress and linked our findings to epigenetic markers of stress and violence. Participants were followed over a period of up to 25-months post-treatment. The FORNET was also disseminated to local staff of our collaboration partners from the South African Universities and an organization working in the townships to warrant sustainability of the therapeutic intervention.