here is the answer, yes they have all taken kick backs.
they do not always do it the way you think.
sometimes they sell "a friend" art work, for half what it will resell for.
sometimes its a addition to a box, in a swiss bank.
even if he did not cover his tracks well on all this, dollars to donuts whatever you do find will be only the part of the iceberg above the water line...what lies beneath, only God knows, and the devils who paid him.
BTW, 50% of research now is bogus according to some researchers.
WHY, because chinese docs will say anything, for a price.
especially if they are still in china, living on a zip salary.
So whatever NIH and pub-MAD now say, take with grains of salt the size of salt licks, unless you know the researchers personally.
it's what this has done to medicine that fumes me.