The charismatic Prasad is credited with changing the shape of Indian politics previously dominated by the elite classes by galvanizing low-caste Hindus into a powerful voting bloc.
He served as Bihar's highest elected official from 1990 to 1997, when he was forced to resign amid allegations that he was pocketing funds meant for farmers in the desperately poor state of Bihar. He spent five months in jail that year, while his wife took over as chief minister. Prasad was also Indian railway minister in 2004-09.
Prasad has maintained he is innocent of the charges, which were filed in 1998. He and his wife, Rabri Devi, were acquitted in a separate case that accused them of accumulating wealth and property beyond their legal incomes.
Prasad could now lose his membership in India's parliament, as the central government in New Delhi is expected to retract last week's executive order exempting legislators from a Supreme Court ban on convicts holding office.
Rahul Gandhi, the second most powerful in the ruling Congress Party, broke with the government in calling the exemption "complete nonsense." Gandhi, a scion of India's Nehru-Gandhi political dynasty, is widely expected to be a candidate for prime minister in 2014.