Sem Asso is the Deputy Chair of the Timika Regional People’s Parliament (PRD). His son, Steven Itlay, Chair of the Timika chapter of the West Papua National Coalition (KNPB Timika), served prison sentences for treason in 2013 and 2016. On 5 January 2019, along with seven other KNPB activists, Sem Asso was questioned by Mimika Regional Police on suspicion of treason. His questioning followed the demolition of the Timika KNPB secretariat building on 30 December 2018.
Beginning in November 2018, a joint police and military team executed the demolition, burning and expropriation of three other KNPB secretariat buildings: KNPB Central office in Jayapura (19 November and 1 December 2018), KNPB Fait Asmat (1 December 2018), and KNPB Fak-Fak (22 January 2019). For these acts of vandalism, the Papua Regional Police have been criticized by respected NGOs including ELSAM, LBH Jakarta, Pusaka, Satu Keadilan Foundation and LP3BH Manokwari.
Sem Assos’s lawyers filed complaints citing procedural errors against the Police and as a result, the Mimika Regional Police temporarily postponed the investigation into charges of treason against him. On 7 January, when he was questioned for the second time, Sem Asso was named as a treason suspect. Sem Asso, Yanto Awerkion, and Edo Dogopia were arrested and transferred to the Jayapura Regional Police Headquarters. No notice was provided to their respective families.