A man named Henryk Siwiak was shot and killed in Brooklyn on Sept. 11, 2001. Because those who died at the World Trade Center were classified as victims of terror, Siwiak was the only murder in New York City that day. But nearly 20 years later, the case remains unsolved. "Everybody heard the shots, but nobody saw anything," NYPD Detective George Harvey told InsideEdition.com. "The person responsible is probably still in the area."