At least two of the 9-11 hijackers probably had a U.S.-based support network, according to a former FBI agent. Danny Gonzalez worked on “Operation Encore,” the still-secret investigation into the two Saudi hijackers who were based in San Diego. Gonzalez told CBS News he’s confident the records of that operation will show the hijackers had help. “19 hijackers cannot commit 3,000 mass murders by themselves,” Gonzalez told the network.