Vietnam’s central police have started investigations into a broker of the Sacombank Securities Company for his role in a stock-price manipulation scheme last year, local media reported Friday.

Le Minh Truyen, 27, allegedly helped Le Van Dung, former chairman of Vien Dong Pharma JSC, manipulate stock prices between May and August last year.

Truyen used ten different accounts to buy and sell a large amount of shares in the Ha Tay Pharmaceutical Joint-Stock Company, police said. But they noted that Dung was the mastermind of the whole scheme.

Under stock regulations, when investors want to buy or sell shares, they must register with securities companies and their brokers are in charge of transactions.

It is unlear on whether the owners of the ten accounts were finally made aware of the illegal transactions.

Dung created a buzz in mid-2010 when he and several collaborators created a false demand by purchasing a large number of Ha Tay shares in in May and June.

Soon afterward, Ha Tay’s stock fell sharply when a total of nearly two millions shares were registered for sale at the same time. It plummeted to VND56,000 at the end of September compared to its peak of VND101,100 in mid-August.

Last November, Dung and three associates were detained pending investigation of their stock transactions.

After the central police announced they are investigating Truyen, Sacombank Securities suspended him from working, VnExpress reported Friday.

Sacombank shares lost VND300, or 3.4 percent, to close at VND8,600 on Friday, though the VN-Index increased 3.2 percent to 410.82, the most since December 13.