An illegal immigrant arrested for possessing a handgun on Sunday had been arrested and sent back to the mainland five times since 2000, a police source said. The man, 32, was first arrested over a robbery case. Police said he had swum from Shenzhen on Friday and taken public transport to Kowloon. He was arrested on Sunday in Yau Ma Tei and a homemade pistol was found in his bag. He was still being questioned last night.