Prosecutors on Tuesday raided the head office of SK Group, widening their investigation into suspicions surrounding catastrophic financial investments made by its chairman Chey Tae-won.

Investigators from the Seoul Central District Prosecutors’ Office descended upon the group’s headquarters in central Seoul early in the morning to search for evidence.

The raid concurrently took place in 10 places, including the office of SK Holdings, the group’s de facto holding company controlled by the group’s founding family, the Cheys.

Among them is SK Gas Co., the country’s biggest distributor of liquefied petroleum gas, located in central Seoul.

They confiscated accounting books, transaction statements and relevant materials which could support allegations of Chey’s embezzlement.

However, the offices and homes of the chairman and his younger brother and group vice chairman Jae-won were not included in the search.

The investigation began in May after it was revealed that the chairman had suffered losses worth more than 100 billion won from his investment in futures. Suspicions arose that Chey may have embezzled company funds for that investment.

Investigators suspect that the tycoon may have pocketed some of a 280 million won ($251,000) investment SK subsidiaries made into Benex Investment, a financial firm owned by former SK Telecom Vice President Kim Jun-hong.

Kim, known as one of the Chey brothers’ closest aides, is standing trial on charges including stock price manipulation.

The younger Chey has been under investigation after it was discovered that 12 billion won was found in a safe belonging to Kim located at his Benex Investment office.

He is suspected of diverting funds from three affiliate companies and subcontractors to create a slush fund.

The same day, another team searched the offices of SK Telecom, SK C&C and a branch office of the National Tax Service as part of a separate probe into bribery allegations involving the conglomerate.

Investigators are also taking issue with the group’s hiring of Lee Hee-wan, a former executive from the tax agency, for a tax-related consulting job. The group paid him 50 million won a month until last year.

The prosecution suspects that the money may have been a post-retirement payoff for undue favors Lee gave to SK while he served at NTS, heading tax probes into the group.

After the raid, an official from SK Group denied the allegations, but said the company will cooperate with the investigation.

By Lee Sun-young (milaya@heraldcorp.com)