The Name of "John Doe"

In the United States, someone who is not known identity is called by the name John Doe (remember the incident the FBI Building bombing in Oklahoma, United States in 1995). And if someone who is not known identity is a woman will be referred to as Jane Doe.
Tradition calls John and Jane Doe in fact comes from murder U.S. President McKinley, on the day Friday, September 6, 1901. The assassin, Leon F. Czolgosz, the day before the murder staying at Riggs House Hotel. At the hotel, Leon uses the pseudonym John Doe, a pseudonym used by police when investigating him.
Finally, until now, every person of unknown identity, the American people called John or Jane Doe.