WASHINGTON - FBI Director Robert Mueller told lawmakers Tuesday he still doesn't know how much it will cost to complete the bureau's computer overhaul, already well over budget and behind schedule. He also refused to state publicly the cost of the initial phase of the Sentinel system, the planned successor to a failed project that was supposed to greatly improve management of terrorism and other criminal cases. "There are certain sensitivities involved," Mueller told the Senate Appropriations Committee's Commerce, Justice and Science subcommittee, explaining that the FBI soon would invite contractors to compete for the work. The FBI has yet...