The Homicide and Organised Crime Investigation Division arrested the key suspect in connection with the murder of Mahajana Eksath Peramuna MP Amarakeerthi Athukorala and his bodyguard.
Officers also found a Smith & Wesson M&P22 firearm that had been stolen by the assailants near a vegetable and fruit stall in front of the Nittambuwa Police Headquarters.
Police have also arrested a former Army soldier who is suspected of stealing the firearm from the well-known Nittambuwa Textile Institute, where the MP and his bodyguard were seeking safe haven.
Meanwhile, the investigation has found that this is the key suspect who dragged the MP out of the jeep and attacked him with a stick.
Eight arrests were made in connection with the murders of MP Athukorala and his bodyguard Sergeant Gunawardena.
Investigations are being conducted on the instructions of SSP Hemal Prashantha, Director of the Homicide and Organised Crime Investigation Division.
By Keerthi Mendis