The government of former Malaysian Prime Minister Najib Razak spent years systematically obstructing probes into the alleged looting of state fund 1MDB while also ruthlessly muzzling critics, according to current and former government officials.

They said the meddling in the investigation by the Malaysian Anti-Corruption Commission (MACC) effectively shut down local inquiries into the scandal at 1Malaysia Development Berhad (1MDB) even as five other countries, including the United States, Switzerland and Singapore, carried out their own probes.

Any suppression of the probe in Malaysia ended abruptly in May when Najib lost power in an election. On Tuesday, Najib was arrested by the Malaysian authorities in relation to a probe into SRC International, a former 1MDB unit, according to an investigating task force.