Rachel, you are partially correct; Pennsylvania has a law on the books called the Slayer's Act (20 Pa. C.S.A. §8801, et seq.) which prohibits a person who participates either as a principal or as an accessory before the fact in the wilful and unlawful killing of another person from acquiring any property or receiving any benefit resulting from the death of that person.

However, §8805 provides, in pertinent part, "One-half of any property held by the slayer and the decedent as tenants by the entirety shall pass upon the death of the decedent to his estate, and the other half shall be held by the slayer during his life, subject to pass upon his death to the estate of the decedent."

Now, I'm no lawyer, but the way I read this, the killing of one spouse by another would convert a tenancy by the entireties to a tenancy in common, and would create a life estate in the slayer which would pass to the decedent's estate upon the death of the slayer.

Just one (lay)man's opinion.

Regards,
Scott