The suspects include two Rohingya Muslims from Myanmar, an Indonesian and a Malaysian, police said.
The inquiry is probing claims that authorities mishandled an investigation into 139 mass graves and more than 12 campsites suspected to have been run by migrant-smuggling gangs.
Human trafficking syndicates are believed to be behind the arrival of 37 Rohingya men on a beach in northern Malaysia on Monday.
Backlash has forced Malaysia to strike a new labor supply deal with Nepal and open talks with other countries. Myanmar has been left out, and its migrant workers are paying for it.
In more than 50 countries it is a crime for a husband to rape his wife, but this is not the case in most of Asia, where campaigners are pushing for legal reform.
The home affairs minister said Roger Ng will have to face criminal charges over the IMDB scandal in Malaysia before he can be sent to the U.S. to face related charges there.
Europe, the world's second-biggest buyer of palm oil, is set to miss a 2020 target to use 100-percent sustainable supplies of the edible oil in food ingredients, experts warn.
At least 150 Rohingya believed to have been preparing for the journey, mostly women and children, have been caught since November, according to local authorities.
Despite the proposed discount, the government decided to cancel the contract this month, according to sources privy to the talks.
"It is not because we want to frustrate or throw out the contract; it is because we are really tight in terms of finance," the prime minister said.
The seizures came just months after Malaysia reported a record bust of nearly 1.2 tons of crystal meth that was disguised as tea in a shipment from Myanmar.
The preacher has been controversial because of his puritan brand of Islam–recommending the death penalty for homosexuals and those who abandon their faith.
Durian may be banned in some airports, public transport and hotels in Southeast Asia for its pungent smell, but the Chinese are huge fans.
Najib Razak was charged with six counts of criminal breach of trust involving govt funds worth more than $1.5 billion, adding to the 32 charges he already faces.
Malaysia's cabinet has ordered the suspension of the colonial-era Sedition Act, widely used to rein in dissent, and is working on doing the same for the death penalty.