It's believed the officers hope evidence from the Rohingya group will lead them to traffickers operating north of Phuket and any renegade law enforcement officers who might have been helping them.
After a dramatic afternoon of price negotiations, the traffickers in the province of Surat Thani put the woman and the boys, all aged 15 or under, on the 8.40pm train for Bangkok on Wednesday night.
The price: 10,000 baht for the lot. It was to be 5000 baht but by creating a competition between the ''sting'' buyer in Bangkok and a second would-be buyer in Malaysia, the Surat Thani trafficker boosted her reward.
The group were among 18 Rohingya women and children who escaped from the government-run family shelter in Khao Lak, north of Phuket, at 2am on Sunday.
Twelve people from that group have since been trafficked across the border into Malaysia, Phuketwan confirmed tonight in a telephone conversation with one of the 12.
The fate of the other six, with no family able to raise cash on their behalf, was to be determined by the trafficker, who kept them in a safe house in Surat Thani.
One of the boys - the oldest is 15 - escaped and his whereabout is not known.
Working with members of the Rohingya community in Thailand, the Superintendent of Phang Nga Immigration, Colonel Neti Kanboon, hatched the plan to get back at least some of the Rohingya.
Late on Wednesday night, the plan succeeded and Immigration officials working with railway police apprehended the Rohingya from Row 57 and took them to Ranong, a port on the Thai-Burma border, for questioning.
Immigration officers should soon have first-hand accounts of how the trafficking network works in Thailand.
The would-be buyer in Malaysia told the trafficker in Surat Thani that he intended to sell the boys to contacts in the Malaysian fishing industry.
Scores of women and children have been enticed from family shelters by traffickers since January, when about 2000 Rohingya were freed from Thai-Malaysia border trafficking camps or apprehended on boats.
The Thai Government gave itself six months to make a decision on the status and future of the captive Rohingya. The deadline is up on Friday.
Since January, news reports have accused renegade officers in the police force and among the military of being involved in the trafficking. Senior officers in the military have consistently denied any conection.