Which, if you want to get pedantic—and yes! let's get pedantic!—probably correlates with a lower probability that the assassination isn't successful. Because if they're irrational, they're going to end up meeting an undercover cop in the parking lot of the local K-Mart or something.
See also: Tiger King. Which is probably the best citation and the best thing I'll type all day.
Ah yes, Tiger King, a well balanced documentary that presents an in-depth look at the practices of murder for hire, and not a lurid tale of entertainment so Netflix can make more money. Popular media, especially shows like CSI and Law and Order, have an incentive to show the rich white folk how resolute the government is, and just how much no one could ever get away with murder. The reality's a bit different, and as recent events have shown, the police aren't above murder anyway. They protect their own and accept murderers in their ranks. So, an ex-cop or current cop is probably the best person to properly incentivize to commit murder.
For them, `p[c] = probability of getting caught` expands to a[c] = probability of getting caught
a[b] = probability of there being no repercussions despite getting caught.
But if we're gonna base today's lesson on how to get away with murder on the show Tiger King, the two step lesson it teaches is: 1. own a tiger sanctuary. 2. feed your husband to the tigers for lunch.
One of them was convicted, and the other wasn't. Sure that's not proof of anything, but it's more than just the netflix documentary that says he did it.
They might also try to kill you themselves. Honestly I think most murderers (or would-be-murderers, or people who [try to] hire murders) are probably not thinking about their situation rationally. Phrased another way: most murders are not rationally motivated. Therefore I don't think the 'rational analysis' approach to predicting who might try to have you dead is likely to work well.
There are exceptions to everything but I think in general the more erratically somebody behaves, the more you should be concerned.
See also: Tiger King. Which is probably the best citation and the best thing I'll type all day.