Four months after Thai activist Wanchalearm Satsaksit was abducted from a street in Phnom Penh, Cambodian authorities have made no progress investigating the case, Amnesty International announced on Monday.

Amnesty International is calling on people around the world to take urgent action by writing a petition addressed to Cambodian Prime Minister Hun Sen to ask for an “effective, thorough and transparent” investigation into the disappearance of Thai activist in exile, Wanchalearm Satsaksit.