"From the beginning he said he would not take any money. It was Rs 14 per day," Jail Superintendent Dilip Pradhan said.
The former Bihar chief minister planted several flower plants in the prison garden, the jail official said.
The jail officials, who had earlier thought of giving Prasad the job of a teacher, later decided to employ him as a gardener.
Prasad wanted to work in the garden to keep himself fit, another jail official said.