PUTRAJAYA, Malaysia — Racing to figure out the depth of the fiscal crisis that awaited him after his inauguration, Prime Minister Mahathir Mohamad and his aides first entered the Malaysian government offices last month to find an alarming sight: oversize garbage bags filled with shredded documents, a snowstorm of loose papers on the floor, even half-consumed food left by former occupants in a hurry to get out.

At the Finance Ministry down the street, Lim Guan Eng, Malaysia’s new finance minister, found computers in which even the highest-ranking bureaucrats were locked out of certain accounts. In some cases, vital files were accessible only to a single person: Najib Razak, the nation’s scandal-tainted former prime minister, who had also served as finance minister.

Evidence of financial malfeasance by Mr. Najib and his cronies helped Mr. Mahathir’s opposition alliance win national elections on May 9, unseating a political force that had governed Malaysia since it gained independence in 1957. But the euphoria surrounding a historic democratic transition has given way to a more sobering reality.

Even without piecing together a single shredded document, Mr. Mahathir, who previously served as prime minister from 1981 to 2003, has discovered that the country is in far worse financial shape than he and his allies had feared. The national debt, tallied at $170 billion by Mr. Najib’s administration, has been reassessed, along with other government liabilities, at $250 billion. That is 80 percent of Malaysia’s gross domestic product.