Cracking corruption cases involving multinational listed companies is getting more difficult, said a veteran graft-buster. Kitty Lau Kit-yin, chief investigator of the Independent Commission Against Corruption, said it takes a lot of time to liaise with foreign law enforcement and investigators also have to study the corporate listing rules in other countries. "The collection of evidence has been difficult. There are different requirements in different countries," Lau said. Most of the cases the commission handled in the past involved only local companies, so tracing the flow of money is relatively easy Top executives of listed companies are usually backed by elite legal teams. Some of those arrested were professional accountants, which made the cases trickier. Lau received a Commissioner's Commendation recently for cracking a fraud case of a local company listed in Singapore. Mah Pat Y, former executive chairman of Daka Designs, Raymond Chow Yiu-man, the company's former chief executive, were jailed for two years and three years and two months respectively in 2011. The former chief financial controller Kevin Leung Kwok-wah was acquitted. They were charged with conspiracy to defraud after ramping up the company's revenue in the 2004 fiscal year by almost HK$10 million. They created transactions to inflate its profit to cover up the company's HK$7 million deficit while applying for a listing on the Singapore Exchange. Lau said it was the most complicated case she had handled. The investigator, who has 20 years of experience, recalled they made the arrests the day before the Mid-Autumn Festival in 2007. "They worked until the next day, the Mid-Autumn Festival. We all wanted to go home to have dinner with our family as soon as possible," she said. Investigators had seized more than 5,000 documents in about 200 boxes. They had to move quickly to find evidence in the piles of document within 48 hours - the maximum period the suspects could be detained. The finally found some bogus invoices for the purchase of mosquito traps.