Investigations

Mine ventilation issues are critical to running a safe coal mine. Here, a rescuer walks through a blocked tunnel in the Crandall Canyon Mine, northwest of Huntington, Utah, where six coal miners were trapped in 2007. Rick Browmer/AP hide caption

Methane monitors are mounted on 30-foot-long continuous miners like this one, and other mining machines, to warn coal miners about dangerous levels of explosive methane gas. File photo hide caption

Methane monitors are mounted on 30-foot-long continuous miners like this one because methane gas collects in pockets near the roofs of mines. File photo hide caption

Sgt. Victor Medina suffered brain damage when an IED hit his truck in Iraq. Even after he was diagnosed with a traumatic brain injury, he found he had to fight to get adequate care. Blake Gordon/Aurora Photos hide caption

Michelle Dyarman, a former major in the Army reserves, was involved in two roadside bomb attacks and a Humvee accident in Iraq in 2005 that left her with serious cognitive problems. David Gilkey/NPR hide caption

Clay Mullins (left), brother of mine disaster victim Rex Mullins, listens as Upper Big Branch miner Stanley "Goose" Stewart tells the House Education and Labor Committee that the mine "was a ticking time bomb" because of problems with ventilation and explosive methane and coal dust. Jon C. Hancock/AP hide caption

A Mexican soldier stands guard as a haul of marijuana and cocaine are incinerated in the background in November 2009. Fighting among the drug cartels — and between government forces and the cartels — has cost nearly 24,000 Mexican lives since late 2006. Jesus Alcazar/AFP/Getty Images hide caption