WHO ARE THE 5 'Bad' MOLES planted by Sam Boss?
These 5 moles should be around the same age according to the temple scene in the 1st movie.
1.
Andy Lau ... Inspector Lau Kin Ming
2
Officer Billy that Shot Yan in front of the elevator in the First movie.
3
The Officer Chun (subordinate to Yeung) that committed suicide infront of Yeung the Third Movie.
4
Leon Lai ... Inspector / SP Yeung Kam Wing
(Sam met with him in the library saying that they have been feeding info to eachother)
Just saw the Extended Version, Yeung was buried nexted to Yan. I think he is still a mole originally planted by Sam Boss , but Yeung just choose to be GOOD like Sam Boss said pick your own path. Yeung did exchange info with Sam but it could just "false info" that were fed to Sam from the top. According to comic book version Sam did wire money into Yeung's account, but Yeung never touches them. However, Yeung is still a shady character remember IA3 where he planted drug in the night club. Just like Wong IA2, who plotted with Carina Lau to kill the Old Big boss.
5???
So who is the 5th mole and If Yeung were not the 4th??
A possible explanation was the conversation between Lau and another inspector from OCTB in Third Movie Chapter 3, he said after Sam Boss died few officers committed suicide or disappeared. So it is not revealed who are these people and they are not that important in the plot.