BROWNSVILLE, Texas (AP) — A Colorado woman who says her husband was shot and killed by drug cartel gunmen while they were boating on a U.S.-Mexico border lake last year says she's still waiting for the attackers to be brought to justice.Tiffany Hartley testified Monday during a congressional field hearing on border security in South Texas launched by Republican Rep. Ted Poe.She recounted how she and her husband, David Hartley, had visited a church on the Mexican side of Falcon Lake. She said gunmen began shooting at them from a boat, hitting her husband in the head.Poe called the hearing in the hopes that it would send a message to Washington that the drug violence plaguing Mexico can bleed over into the U.S. Poe's district stretches north and east of Houston.