However, by December 1977, no arrests had been made, though police were investigating the deadly rivalry between the Joe Boys and Wah Ching. The reward was eventually collected by Gan Wah "Robert" Woo of the Joe Boys. Woo had been arrested in March 1978 for participating in another gang skirmish on February 15 in Portsmouth Square, a shooting that left two Wah Ching members wounded. He gave the police a recording of Tam conversing about the massacre; subsequently, Woo was kept in protective custody after he had been identified as the informant.