A former senior official at Goldman Sachs Group Inc. has been subpoenaed by American authorities investigating a Malaysian government investment fund, according to reports Tuesday. Tim Leissner, the former chairman of the Southeast Asian division of the investment bank, was issued a subpoena after he resigned in February.

Leissner worked on several significant deals for the state-run fund, the 1Malaysia Development Bhd (1MDB), which together netted hundreds of millions of dollars for the investment bank, Bloomberg reported.

Goldman placed Leissner on leave after reviewing his emails and finding that he allegedly sent an unauthorized and inaccurate reference letter for an individual to another financial firm in 2015, the Wall Street Journal reported citing sources. The report added that the letter was not connected to the bank's work with 1MDB and that Goldman did not find anything wrong with Leissner's dealings with the fund. While 1MDB has denied the allegations, Goldman declined to comment on the issue, the Journal said.

The FBI and the U.S. Department of Justice authorities are investigating Goldman over allegations of money laundering and corruption as an adviser to the 1MDB, which has been marred by scandal since last July, when hundreds of millions of dollars from the fund were traced to the personal bank accounts of Malaysian Prime Minister Najib Razak. Allegations against Najib were first made in a July 2015 report by the Journal, which said that investigators had traced the money from an account at Falcon Private Bank in Singapore to accounts in Malaysia. Najib has consistently denied the allegations.

Singapore has seized several bank accounts in the past couple of months, as part of its investigation into possible embezzlement. Apart from the U.S. and Singapore, investigations into the fund's finances also have been reportedly opened in Malaysia, Switzerland, Hong Kong and Abu Dhabi.