Last week, Arcan Cetin, an immigrant from Turkey, shot and killed five people at a mall in Washington state. Cetin is a green card holder and not a U.S. citizen, and therefore not able to legally vote--but somehow was able to vote in the last three elections, including the presidential primary in May. Washington does not verify citizenship during voter registration.
KING 5, a news station in Washington, reports that federal investigators confirmed that Cetin was indeed a registered voter even though it is not legal for him to do so. They did not reveal which party, if any, he was registered to.