I would support the maximum lawful penalty for anyone proven to be dealing drugs to children (especially a teacher who sells crystal meth to students). I have little confidence that the Sri Lankan government will handle cases like this seriously.
If there are credible concerns about unpaid taxes or suspicious overseas transfers to Kuwait, the proper authorities should be tipped off and allowed to investigate trashcans. If the evidence proves tax evasion or another offence, the person should be arrested, named publicly and prosecuted through due process.
It doesn't matter if he or she's retired, or old or has excuses.