- Associated Press - Wednesday, July 23, 2014

BOULDER, Colo. (AP) - An irregular heartbeat is being blamed for the death of runner at the Boulder Spring Half Marathon this year.

Twenty-year-old Jessica Dillon of Castle Rock collapsed near the finish line of the race in May. On Wednesday, Boulder coroner Emma Hall said the Colorado State University student died because of the irregular heartbeat combined with a condition that shrinks the size of the heart chamber but thickening its walls.