Five men and three women were arrested in Singapore and Malaysia on Wednesday in relation to a kidnapping that took place earlier this week.
A business trip gone wrong had left two Singaporeans trapped in a Penang hotel, kidnapped for about two days before their rescue.
The brothers, aged 28 and 27, had set off together for Malaysia last Sunday, the Singapore Police Force said in a statement yesterday.
But the day after they left, the elder brother's fiancee received a call from an unknown Malaysian mobile number. She was asked to pay US$250,000 (S$351,000) for his release.
That night, at around 10.55pm, the 29-year-old reported the case to the Singapore police.
Officers from the Criminal Investigation Department (CID) and Police Intelligence Department responded immediately, starting investigations and ground enquiries.
Working with the Royal Malaysia Police (RMP), they pursued all leads and intensified efforts to establish the whereabouts of the victims and locate possible suspects.
They established the suspects' identities and tracked down the victims to a hotel in Penang
On Wednesday, Malaysian police officers raided the hotel and arrested four Malaysian men. They rescued the brothers, who were unharmed.
In a coordinated strike on the same day, CID officers nabbed four Singaporean suspects connected to the case - one man and three women, aged 26 to 54.
No ransom money was delivered.
According to Chinese evening paper Shin Min Daily News, the brothers are the sons of a wealthy businessman and had been kidnapped when they went out for dinner after arriving in Penang.
According to police, three of the four suspects arrested in Singapore will be charged in court today with the offence of putting a person in fear of harm in order to commit extortion with common intention. They face jail terms of up to five years, with caning.
The police are still investigating the case against the remaining female suspect.
Deputy Commissioner of Police (Investigations & Intelligence) Tan Chye Hee expressed his gratitude and appreciation to the Malaysian police "for their unequivocal support in the joint cross-border investigation of the kidnapping for ransom case".
"Undoubtedly, the close cooperation between (the) Singapore Police Force and RMP was instrumental in the swift arrest of the suspects, resulting in the safe release of the Singapore victims," he said.