25-year-old Balwinder Singh, lodged in jail four days back, committed suicide by hanging himself with a turban from a scaffolding installed for construction work in the jail complex, they said.
Singh, along with his brother, was sentenced to three years' imprisonment and a fine of Rs 1,100 on October 30 in a case registered against them in July, 2009.
District and Sessions Judge J K Dhir has ordered a judicial inquiry into the alleged suicide.
A medical board, consisting of three doctors, was constituted to perform the postmortem which would be videographed, police said.