Siena, February 15 - The ex-chairman of struggling Monte dei Paschi di Siena (MPS), who was jeered at by a crowd of protesters earlier Friday, answered all prosecutors' questions, his lawyers said. They issued a statement after Giuseppe Mussari, who resigned from MPS last year, was called in for questioning along with Antonio Vigni, the ex-general manager. Mussari is now reportedly under investigation for market manipulation, fraud, obstructing the work of banking watchdogs, issuing false statements and - as of Thursday - collusion in obstruction of proper oversight with the former head of the MPS finance department Gianluca Baldassari and Vigni. A small crowd of angry protesters greeted Mussari as he entered the local courthouse for questioning by prosecutors, throwing coins and shouting "thief" and "buffoon". The Italian central bank announced last month that while scrutinizing MPS documents, they found a previously undisclosed series of derivative and structured-finance deals produced losses in excess of 720 million euros under Mussari's watch. MPS, Italy's third-largest lender and the world's oldest bank, is creaking under the weight of the failed derivatives transactions and alleged corruption which has involved some of the bank's top managers. Besides the Siena investigation, separate MPS probes are underway in Rome and Trani in the southern region of Puglia.