Mathew Siloma (Councillor Arash ward) is one of several Maasai local government leaders from the Loliondo region of northern Tanzania who were arrested on June 9 2022, after being called into a consultative meeting with the Ngorongoro District Commissioner. Siloma, amongst others, has been charged with the murder of police officer Garlus Mwita (killed during a protest on June 10 2022), despite the fact that he was arrested the day before Mwita was killed. The consultative meeting on June 9, and the protest on June 10, were both linked to the ongoing demarcation of ancestral Maasai lands and related displacement of Maasai communities to make way for the Otterlo Business Corporation's planned commercial conservation and hunting reserve.

Other arrested Maasai leaders are Joel Clemes Lessomu.,Shengeni Joseph Killel, Simoni Nairiam Orosikiria, Luka Kursas, Taleng'o Twambei Leshoko, Damiani Rago Laiza, Moloimet Yohana and Kijoolu Kakiya.