Hazardous materials experts determined the powder was harmless, but sending threats through the U.S. mail is a federal offense, punishable by fines and up to 20 years in prison.
The Postal Inspection Service, the U.C. Irvine Police Department, and the Federal Bureau of Investigation continue to follow up on leads.
Anyone with information in the case is urged to call U.S. Postal Inspectors at 1-877-876-2455, and select option 2. Callers may remain anonymous.
The U.S. Postal Inspection Service is one of the oldest federal law enforcement agencies in the country. For more than 200 years, Postal Inspectors have protected the U.S. Postal Service, secured the nation's mail system and ensured public trust in the mail.