Like many states, Florida's probate code includes a "Slayer Statute" located at Section 732.802, Fla. Stat. This statute provides that persons who intentionally kill, or procure the killing, of another person may not receive benefits under the deceased person's Will. The statute also applies to forbid receiving benefits under a life insurance policy covering the deceased person.
These situations involving a Will or life insurance make sense in terms of what we'd expect if someone kills another person. Perhaps a little less expected is what happens if persons own property jointly--such as joint tenants with right of survivorship. The Slayer Statute applies to this situation as well. In that case, the killer is treated as if he or she did not survive the deceased person. In other words, the property does not vest in the surviving killer.
So if a person kills another, what happens to the killer's rights under a Will, life insurance or joint tenancy? In essence, the property passes as if the killer had predeceased the decedent. So for example, in the case where a killer is named as a beneficiary under a Will, if the Will provides what happens if the killer dies before the testator, then that kicks in if the testator is murdered. Under the probate, the killer would receive nothing.
The Slayer Statute makes for some interesting cases. Over 20 years ago, I represented a life insurance company who denied a claim by a family member who was named beneficiary of person who drowned under suspicious circumstances. The drowning occurred while the two were out canoeing on a lake and one fell over and couldn't get back in the canoe--resulting in his death. Investigation of the death showed that the deceased person not only drowned but he had a laceration with wooden splinters in his forehead--the kind of splinters a canoe paddle would make! Needless, to say, we won.