Pursuit of a KillerMovie

This is one of those -"who did it" -murder movies put out by Shaw Brothers. In this one, a bunch of Mainlanders come to Hong Kong for a better life. Instead, these Mainlanders are jobless and wind up killing, robbing, and selling drugs for a Dai Lo. Tired of getting chicken scratch from their Dai Lo for all the work they've done, the Mainlanders (about 4 or 5) decide to do a big job for themselves by trying to rob a jewelry store. The heist goes awry with all the Mainlanders being apprehended by the HKRP. They all to go to jail and do their time and get discharged. Once out, the Mainlanders are getting "rubbed off" one by one and the HKRP do not have a clue. Luckily, one member, Yeh Hung (Lo Meng), of the Mainlander gang is still in jail who still has time. So, Inspector Wong (Jason Pai Piao) decides to cut Yeh Hung loose and let him walk the streets as bait to bring the killer out.