EARLIER this week, a man with a foreign accent rang from an overseas number.

'I'm calling on behalf of my clients,' he said. 'What I want to know is: have you met Anthony Soh? Is he honest?'

It's a question hundreds of investors in Jade Technologies must be asking themselves now.

Dr Soh's takeover bid for the company has collapsed, along with Jade's share price. The Commercial Affairs Department (CAD) is probing his probity; the Securities Industry Council (SIC) is investigating too.

There has even been hysterical talk of Australian gangland involvement in the Opes Prime episode, what with the high- profile arrival this week in Singapore of a former underworld bruiser.

There is probably no quick answer. But it's clear that controversial takeover bids are not alien to Dr Soh. In 2005 he had tried to buy a small bank in Bali, PT Bank Sri Partha. Although negotiations went on for two years, the deal collapsed in 2007. A source connected to the bank told BT, among other things, that Dr Soh had persistently been unable to secure financing. When contacted last night, Dr Soh claimed he pulled the plug when he found out the bank did not have tier one status. The debate is still rumbling, but the bank itself has been sold to Mercy Corp and the International Finance Corporation.

Other corporate deals seem more straightforward. He was on the board of China Medstar, which provides radiotherapy in China, but resigned when it listed on London's secondary market, AIM. As a representative for four years of a UOB investment fund, he was on the board of Cordlife, a cord blood bank now listed in Australia. Steven Fang, chief executive of Cordlife, says they haven't spoken for three or four years.

Also not speaking was the Singapore Medical Council, which is keeping mum on whether there were any disciplinary cases in his record as a doctor. However, a report in The Straits Times revealed that in November 1992, a four-day inquiry was held against him. He was acquitted but 'strongly admonished' for his handling of a patient who later died of malaria. Dr Soh confirmed this case and claimed he had taken responsibility along with a locum. He added that he no longer has a practising certificate, giving it up 'three to four years ago' when the continuing requirements proved too onerous.

A healthcare business he founded in 1990 (Welfare Hearing Service, in Balestier Road) is now run by his wife, Jane, who, according to its website, was previously a qualified staff nurse with the Ministry of Health. The website states she was trained by Dr Soh, a 'qualified audiologist trained in the University of Queensland, Australia'.

Other details cropped up in the course of two meetings and several telephone conversations. Dr Soh said he had been involved for many years in China and Hong Kong since the late 1990s. 'I've done, for example, a $400 million power plant in Henan before. I've done a township in Jiangsu, Dafong Shi, bringing JTC into the area, to try and build a port.'

He told BT in January that in 2007, he did more than 10 property transactions, which apparently included making a pile from the en bloc fever. 'I've been in the investment business for more than 10 years,' he said.

He portrayed himself as a defender of the small man, a corporate fixer specialising in quick turnarounds. 'My greatest strength is in two areas - fund raising, and execution,' he said then. 'I sat on the boards of more than 10 companies in the past. The day they went public was the day I tendered my resignation.'

He said that he has moved to working with public companies and that he was grateful to the many small household investors who bought shares in Jade and E3 (another listed firm he has an interest in) - 'even when they don't know what business we are in, and they don't know what it stands for. But they have so much faith in me.'

That faith has been sorely tested this past month.