U.S. Maj. Gen. Harold Greene was visiting an Afghan military training academy Tuesday when he was shot dead by an Afghan soldier, who was subsequently killed. Afghan troops who knew the attacker say he disliked the Taliban and they aren't sure what his motive was. U.S. Army/Getty Images hide caption

itoggle caption U.S. Army/Getty Images

U.S. Secretary of State John Kerry talks with Afghan presidential candidate Abdullah Abdullah at the start of a meeting at the U.S. Embassy in Kabul on Friday. Kerry sought Friday to broker a deal between Afghanistan's rival presidential candidates. Jim Bourg/AP hide caption

itoggle caption Jim Bourg/AP

Bryan McDonel and his father, Mike, both served multiple tours in Iraq with the National Guard. Bryan was first prescribed painkillers before his deployment, and his dependence on medication prompted a downward spiral. Quil Lawrence/NPR hide caption

itoggle caption Quil Lawrence/NPR