The Church committee in 1976 revealed the CIA development and use of a system for delivering self-propelled, poisoned Flechette darts from devices like an umbrella. Imagine how much more sophisticated, more miniaturized devices might be available today. The firing mechanism might very well be hidden in a prosthetic, false finger. Or in a false tooth. Or under his hair (I said it was miniaturized).
But it won’t be investigated for 20 years and the records will be sealed for 75 years after that. So keep taking your CoQ10 everybody!