A key suspect, who is the aunt of a female doctor allegedly connected to a bogus tourism company, turned herself in to police on Tuesday, insisting she was also a victim of the fraud.
Phongphan Siriwat, aunt of Dr Phannarat Chantharamani, surrendered to Central Investigation Bureau (CIB) chief Thitirat Nongharnpitak, saying she wanted to prove her sincerity and show she had no knowledge of the scam.
She insisted she was one of the victims.
Ms Phongphan, who has been charged with public fraud, also prepared to submit a bail request with a land title deed worth 800,000 baht as surety.
Police say Dr Phannarat is believed to have escaped to the Philippines ahead of the Songkran festival, days before the scam, which caused more than 60 million baht in damages, was exposed.
Arrest warrants were issued for the doctor and later for Ms Phongphan and the doctor's boyfriend, Apiwat Akkaradetm, whose previous name was Theerayut Burassakarn.
He is reportedly still in the country, according to officials.
During a police inquiry, Ms Phongphan said she was persuaded by Mr Apiwat to work in the administration department at the couple's company in October last year.
Although her niece was the company's executive, the firm was mainly overseen by the boyfriend, she said.
Ms Phongphan's duty was to inspect hotel rooms, take pictures and send them to Mr Apiwat via the Line application.
She also invested 1.3 million baht in the business and received dividends until last month when Mr Apiwat claimed he was unable to pay her as the company had failed to collect money from its clients.
After that, she lost contact with him.
The woman said Dr Phannarat has been in a relationship with Mr Apiwat since 2014.
The man also allegedly lured the physician's relatives into the scam, causing them to lose more than three million baht.
Ms Phongphan said her niece decided to flee abroad as she had an argument with Mr Apiwat who also threatened her.
In another development, Pol Lt Gen Thitirat said police are in the process of seeking an arrest warrant for another suspect involved in a high-profile tour scam to Japan, orchestrated by alleged fraudster Pasist Arinchayalapis, alias Sin Sae Shogun.
He also instructed investigators overseeing the case to quickly wrap up the probe summary and forward it to prosecutors by next week.
"The case has caused huge damages. Although some of the money was returned to the victims, there will be no compromise in this case as a lot of people were defrauded," the CIB chief said.
Besides the two cases, Pol Lt Gen Thitirat also ordered investigators to step up efforts to track down Sawat Saengbangpla, 79, ex-chairman of Chulalongkorn University Savings Cooperative, who is accused of luring people into a bogus lottery investment scheme, causing damages exceeding one billion baht.
A preliminary probe indicates Mr Sawat is still hiding in Thailand.
Pol Lt Gen Thitirat said police were compiling evidence to find whether there were other accomplices in the case or whether he acted alone.
Checks of the suspects' financial transactions showed none of the money taken from the victims had been transferred to other people's accounts or used to buy property.
Mr Sawat's relatives and acquaintances will be summoned for questioning as the probe widens, he added.
In a separate case Tuesday, the Crime Suppression Division (CSD) received complaints from 20 product distributors who claimed they were duped by a company to invest in a Chinese online advertisement scheme, causing 30 million baht in losses.
The victims said paid 75,900 baht for each ad, but the company did not keep its promise to have their products promoted by popular Chinese idols on a well-known online shopping site based in China.
The company had also guaranteed a high sales volume.