Police are keen to find a witness who may have filmed part of a street robbery in Plymouth on his mobile phone.The man helped chase the attacker, shook the victim's hand and told him he had footage of the incident in a service lane.But he left without leaving his details.Police said the robber snatched the handbag of a woman walking with her partner near the railway station.Her partner gave chase and the thug dropped the bag in the lane running parallel to the tracks and Glen Park Avenue.But the...
