Sukhdev was a member of the Hindustan Socialist Republican Association (HSRA), and organised revolutionary
cells in Punjab and other areas of North India. He was the chief of Punjab unit of HSRA and instrumental
in taking decisions.
Sukhdev participated in numerous revolutionary activities such as a prison hunger strike in 1929; he is
best known for his assaults in the Lahore Conspiracy Case (17 December 1928). He is best remembered for
his involvement in the assassination of Deputy Superintendent of Police, J. P. Saunders, on 17 December
1928, by Bhagat Singh and Shivaram Rajguru, undertaken in response to the violent death of the veteran
leader Lala Lajpat Rai.
Lahore Conspiracy case
Sukhdev was the prime accused in the Lahore Conspiracy Case of 1929, whose official title was "Crown
versus Sukhdev and others." The first information report (FIR) of the case, filed by Hamilton Harding,
senior superintendent of police, in the court of R.S. Pandit, the special magistrate in April 1929,
mentions Sukhdev as accused number 1. It describes him as Swami alias villager, son of Ram Lal, caste
Thapar Khatri. After the Central Assembly Hall bombings in New Delhi (8 April 1929), Sukhdev and his
accomplices were arrested, convicted, and sentenced to death.
On 23 March 1931, Thapar was hanged in Lahore jail, along with Bhagat Singh and Shivaram Rajguru. Their
bodies were secretly cremated at the banks of the River Sutlej.