Around this time, he joined Kumpulan Mujahidin Malaysia (KMM), and became the chief of the group's Selangor chapter. According to the Malaysian Special Branch, Zainuri was linked to the attempted assassination of Nivashini Rajeswaran on 25 May 1998, and the assassination of Lunas assemblyman Dr Joe Fernandez. In 2000, he and another KMM militant were involved in bomb attacks in Kuala Lumpur.