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A Malaysian woman walks past a billboard with the 1MDB logo at the funds flagship Tun Razak Exchange construction site in Kuala Lumpur, Sept. 22, 2015. GETTY IMAGES/MANAN VATSYAYANA/AFP

Yeo Jiawei, a former employee at BSI Singapore — a private Swiss bank, garnered $13.6 million within 15 months through illegal deals with the scandal-hit Malaysian state fund 1Malaysia Development Berhad (1MDB), prosecutors said Tuesday. However, the ex-BSI banker said the earnings were simply “referral fees” that were “directly earned.”

Singaporean prosecutors made the allegations on the last day of Yeo’s trial that lasted for 12 days. He faces four charges of obstructing justice. Deputy Public Prosecutor Tan Kiat Pheng told the banker that it was “quite unbelievable” that Yeo accumulated $13.6 million only by being “an ‘introducer, intermediary, independent consultant or relationship manager.’”

Prior to leaving his job BSI in July 2014, Yeo’s net income was just over $1.4 million. But, by 2015, his assets grew to three properties in Singapore worth $4.3 million and two properties in Australia with total value of $4.5 million, the prosecutors alleged.

“I put it to you, your illicit wealth after your BSI days arose from deals that you were involved in together with [Malaysian tycoon] Jho Low, Eric Tan Kim Loong [Low’s close business associate] and Mohamed Ahmed Badawy Al Husseiny [ex-CEO of Abu Dhabi state fund’s Aabar Investments PJS],” Tan said, according to the Strait Times.

Low, Eric Tan and Al Husseiny are being investigated over corruption allegations at 1MDB.

However, Yeo defended his earnings saying that Singapore’s Commercial Affairs Department “forgot these are referral fees earned from one of the biggest sovereign wealth funds in the world,” referring to Aabar, the newspaper reported.

Furthermore, he also brought in ex-BSI banker Yak Yew Chee’s case where Yak gathered $18.9 million from BSI from 2011 to 2015. Yak, who formerly served as a senior vice president at BSI Singapore and as private banker to Low, was jailed for 18 weeks earlier this month for forgery and failure to disclose suspicious transactions linked to 1MDB.

But, the prosecutor pointed out to Yeo that it took Yak four years to earn the amount but only one year and three months to amass $13.6 million for Yeo, who also denied any wrongdoing in establishing fund structures for fake entities allegedly associated with Aabar. Investigators suspect that the fake establishments were used to put in 1MDB money.

“I’m a victim too. There are many people in the bank that have dealt with Aabar, but everything has fallen to me,” Yeo said.

The verdict on the matter is expected to be delivered on Dec. 21.

Malaysian Prime Minister Najib Razak had formed 1MDB to spur Malaysia’s economic growth. Investigators reportedly believe that over $1 billion from the state-run fund can be traced to the prime minister’s private bank accounts. He has denied any wrongdoing.