What kind of evidence would you expect to find?
As with everything related to the JFKA, I don't "expect" anything.
If there were evidence the KGB had a sophisticated program capable of creating Manchurian candidates and there were any evidence Oswald had been subjected to such treatment in Minsk, and if his action upon his return to the U.S. and on the day of the JFKA gave any indication of such programming, that would be interesting and something other than raw speculation.
The problem with much CT theorizing is that the inferences and speculation greatly outrun the evidence. Reasonable inferences and speculation fill in gaps in the evidence - they don't drive the bus (except in some CT theorizing).