The successful assassination of an autocrat creates a highly significant 13 percentage point increase in the probability of democratic transition, compared to the case where the assassination attempt failed. Meanwhile, the successful assassination of democrats produces no change in institutions using the Polity IV measure. Democratic institutions thus appear robust to the assassination of leaders, while autocratic regimes are not. Similar results are obtained using the percentage of regular future leadership transitions from Archigos as the criterion – successful assassination of autocrats creates a 19 percentage point increase in the probability that future leadership transitions occur by regular means, whereas there is no change in the probability that future leadership transitions occur by regular means following a successful assassination of a democrat.

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<...> the short-run move to democracy is particularly large following the assassination of long-tenured autocrats, for whom a successful assassination increases the probability of democratic transition in the next year by 20 percentage points relative to a failed assassination. The distinction between tenure is less clear with time however. The most interesting result <...> shows that democratic transitions following assassinations of autocrats appear to be sustained 10 years later. The point estimate suggests that initially autocratic regimes are 19 percentage points more likely to be democracies 10 years after the attempt if the assassination succeeded rather than failed <...>

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These results show that, following a successful assassination of an autocrat, leadership transitions 11 to 20 years after the attempt are 21 percentage points more likely to be regular. Following a successful assassination of a longtenured autocrat, leadership transitions 11 to 20 years after the attempt are 42 percentage points more likely to be regular <...>

http://www.nber.org/~bolken/assassinations.pdf