Charges against 9/11 suspects were dropped "without prejudice" -- a procedural move that allows federal officials to transfer the men to trial in a civilian court and also leaves the door open to again bringing charges in military commissions.

Currently no suspects stand charged in the terrorist attacks that killed nearly 3,000 people on Sept. 11. U.S. officials sent notification to Congress and families of 9/11 victims Friday afternoon.

The Obama administration decided in November to remove the five suspects -- including self-professed 9/11 mastermind Khalid Sheikh Mohammed -- from a military trial after $100 million was spent on their prosecution and on construction of a state-of-the-art courthouse at Guantanamo Bay specifically to facilitate their military commissions.