Jaswinder Singh, son of SGPC member Ranjeet Singh, was arrested yesterday from Ludhiana by Mohali Police.
Jaswinder is a class 12 pass-out and currently unemployed.
He is suspected to be one of the prime accused in the murder case and, as per the complainant, had even threatened the victim, Mohali SSP Gurpreet Singh Bhullar said.
Amarpreet, 32, was killed on last Wednesday night and his cousin Gaganjot Singh and the latter's friend Simarjeet Singh sustained bullet injuries when a group of youths fired at them after they objected to parking of vehicles outside their house.
Omkar Singh and Sunbir Singh, hailing from Amritsar, were arrested on Wednesday immediately after the crime.
Raids are on and other accused would be arrested soon, the officer claimed.