Local people of Muraripukur discovered the body of Kanhaia Sahoo in a sitting-position on the front seat of the vehicle at around 11 AM.
"The person was hit by a bullet on the left side of his chest. We have also recovered a pistol from near his feet inside the car," a senior officer of Kolkata Police said.
"The bullet was fired from a very close range. It has pierced the person's chest and went out through his back," he added.
Primary investigation revealed that Sahoo was busy in painting walls for TMC for the upcoming Assembly polls till 1.30 AM, he said.
"We have spoken to those who were with him in the wall painting and found that Sahoo had received a call on his mobile and had a very agitating conversation. We're going through the call list of his phone," he said.
The victim used to drive the goods vehicle from which the body was found, the officer said adding that police were also talking to the owner of the vehicle in connection with the incident.