The man, Jagdish, had come to spend the night at a homeless shelter.
A man was found dead at a night shelter in Uttar Pradesh on Tuesday.
Jagdish came to spend the night at Raen Basera, a homeless shelter home run by the municipal corporation in Aligarh, and was declared dead in the morning.
Chand Mohammad, another man who sought refuge at the homeless shelter, claimed that Jagdish was an alcoholic and used to sell blood to the hospitals.
The police has sent his body for post-mortem and has started investigating what led to his death.
"The cause of death is not clear. Anything substantial about it can only be said after the post-mortem is done," said Aligarh Municipal Corporation's Press Relation Officer Sabhapati Yadav.