As top officials in a state government of India, Arvind and Tinu Joshi should have led a comfortable middle-class existence.

But an income tax investigation found more than two dozen apartments, nearly 400 acres (160 hectares) of land, piles of jewelry and foreign currency stashed in bank lockers and millions of rupees stuffed into pillowcases and plastic bags in their home.

Tax authorities valued the Joshi's wealth at more than $80 million — for a couple who likely made about $2,500 a month combined, given their seniority and positions in the Madhya Pradesh state government.

The discovery, which newspapers called the largest case of unexplained wealth ever linked to an Indian government official, startled a country usually inured to tales of graft and corruption.

Recent scandals include irregularities in a telecoms deal that cost the country billions and India's hosting of the Commonwealth Games, which was marred by allegations of corruption and mismanagement.

Speaking generally on corruption, the Supreme Court this week rapped the government for failing to act against Indians who parked unaccounted money in foreign banks, calling it "the plunder of national wealth."

The Joshis had distinguished government careers over three decades, including stints in the prime minister's office and the defense ministry. Last year, Arvind Joshi was the top administrator in Madhya Pradesh's water resources department, while Tinu ran the women and child welfare department.

Then, in February, investigators raided their home as part of a probe into another official's unexplained wealth. Around 30 million rupees (nearly $70,000) stuffed into plastic bags and pillow cases were found in their home in Bhopal, the state capital.

The Joshis were suspended on suspicion of graft as the tax investigation developed. The 7,000-page report on their assets released by state tax authorities this week was seen as a first step to eventually prosecuting the Joshis, who have not spoken publicly since the investigation started.

Officials have yet to detail their theories as to how the Joshis amassed such an enormous fortune without detection.

The top official in Madhya Pradesh, Chief Secretary Avni Vaish, told the Hindustan Times newspaper, the state was verifying the report before taking action against the couple.