Police said Ravinder Yadav jumped off the Botanical Garden metro station and fell on the roof of a parked car, apparently after he was accused of theft by the conductor of an auto stand.
He was rushed to the district hospital from where he was referred to a hospital in Delhi considering his critical condition.
Other auto drivers at the stand said parking contractor Vinay had earlier accused Ravinder of stealing Rs 17,000. Though he had pleaded innocent, the contractor had called some policemen who had assaulted him and took Rs 8,000.
"The matter is being investigated. Any policeman found guilty would be punished. A suicide note has been recovered from him," Deputy Superintendent of Police Shiv Ram Yadav said.