Ron Unz put out a long article yesterday. He says that a contact of his who is well-connected in the mainstream conservativism movement told him that Kirk, earlier this year, rejected an offer from Netanyahu to have Turning Point lavished with shekels. Turning Point had been funded by Jewish money from the outset and the Jewish lobby was furious that Kirk was not living up to his end of the bargain. Unz goes on to say that Kirk rejected a meeting with Netanyahu just two weeks before his death. Trump and the GOP were also get keen to get Kirk back onside because they're terrified of Netanyahu.
Unz, however, did go on to say that despite the zionists having the means and the motive (and the extensive history of political assassinations), there is no evidence to suggest a professional Mossad/CIA hit actually took place. Sometimes coincidences do occur.
If there was agency involvement (me talking now, not), then I think it only goes as far as discord grooming. Theories about patsies and establishment-wide cover-ups are just too complex to be entertained.