Mohd Faris Anuar and Muhamad Wanndy Muhammad Jedi, aged 20 and 25 respectively, were identified as the men involved in the beheading of a Syrian man in a video posted to Facebook on Feb. 22, said Ayub Khan Mydin, the police counter-terrorism division's deputy chief.
Wanndy traveled with his wife Nor Mahmudah Ahmad to Syria on Jan. 26, while Faris went last September, said Ayub Khan.
Malaysia is expected to tighten anti-terror laws used to curb militant activities when parliament resumes this month, Reuters reported.
Prime Minister Najib Razak said last November that stronger laws were needed to curb militants, who now have the equipment and logistics to plan "lone wolf" attacks, establish ISIL cells and form connections with other militant groups in the region.
The country has arrested 40 citizens suspected of militancy and identified 39 Malaysians already in Syria and Iraq.
Malaysian militants have used Facebook and other social media sites to lure recruits, attracting thousands of followers online.