[Scythian]

Singapore MAS was in the dark for more than 3 years without knowing US DoJ investigation on 1MDB until statement released 3 years later in July 2016

"United States Seeks to Recover More Than $1 Billion Obtained from Corruption Involving Malaysian Sovereign Wealth Fund
Attorney General Loretta E. Lynch announced today the filing of civil forfeiture complaints seeking the forfeiture and recovery of more than $1 billion"

https://www.justice.gov/opa/pr/united-st...-1-billion

[Oasis]

No matter how many times that the money is transferred, the electronic trail can be found.

The bank can trace the receiver of the money and report them to the police.

Why OCBC did not trace the money and report them to the police ?

Reactive. 
Arrest them, charge them and feed them
After several years, release them and they are loaded.
Can victims recover their money?