[Wuli]

I am with you, on how the conversations the defector group had with Kim Jong Nam may have been the immediate cause of his assassination.

It all also suggests to me that the defector network is not so tight and secure within itself, that the regime in the north has its own agents sent in as moles to join it and report on its activities.

[TigerLikesRooster]

Yes, there are definitely moles. Furthermore, I think Kim Jong-nam was always watched by N. Korean agents. So it would not be hard for N. Koreans to find out that somebody from defector's organization is repeatedly seeking out Kim Jong-nam, which is a red flag.