I am currently writing a novel about local police solving the case of a fugitive from MA being found dead in NY. At what point would the FBI get involved?

Question: I am currently writing a novel about local police solving the case of a fugitive from MA being found dead in NY. At what point would the FBI get involved?

Perhaps never.

The FBI normally would only become involved in a homicide if it was:

The murder of a federal employee during the performance of their role as an employee, including some military members

The murder of a federal witness

The murder of a person on federal land, in a federal facility, or on a Native American reservation.

A murder linked to organized crime, an intelligence operation, terrorism (domestic/foreign), or that of a high level foreign national.

A high profile event such the work of a potential serial offender whose resolution could attract a great deal of publicity for the FBI.

Murders are considered to be “local” and “state” affairs so the FBI leaves their resolution to the applicable agencies.