True. But in Vermont, it's a felony punishable by 7 years in prison:

Title 13: Crimes and Criminal Procedure

Chapter 1: General Provisions

§ 5. Accessory after the fact

A person not standing in the relation of husband, wife, parent, grandparent, child, grandchild, brother, or sister, by consanguinity or affinity, to an offender, who, after the commission of a felony, harbors, conceals, maintains, or assists such offender with intent that he or she shall avoid or escape arrest or punishment therefor, shall be imprisoned not more than seven years or fined not more than $1,000.00, or both.

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However, she was his wife, so that doesn't apply either. If she wasn't otherwise related, the State would have 3 years to charge her before the statute of limitations ran out.

However, if they find out that she did anything to actually help him in any way prior or during the actual crime, they could charge her with the homicide:

§ 3. Accessory aiding commission of felony

A person who aids in the commission of a felony shall be punished as a principal.

Then there is no statute of limitations.