Bulgarian prosecutors said Thursday they were launching a probe against parliament's deputy speaker Hristo Biserov over alleged money laundering, days after he resigned from his job.
Prosecutors said they were investigating Biserov and his stepson for "tax crimes, money laundering and document fraud," after finding they had wired large sums between accounts they held in various European countries.
Some of the money was also transferred to offshore company accounts in the Seychelles, it added.
Local media reported the sum in question was $450,000 (333,000 euros).
The 57-year-old Biserov, a veteran politician who has served in six Bulgarian parliaments since the fall of communism in 1991, offered his surprise resignation on Monday, citing "personal reasons."
A day earlier, he had resigned as deputy chairman of his liberal Turkish minority Movement for Rights and Freedoms Party (MRF), a vital supporter of Prime Minister Plamen Oresharski's minority technocrat government.
Oresharski took office in May but has faced continued pressure to resign from thousands of angry Bulgarians, who demand an end to corruption in politics.
Biserov has not made any public comments so far.