Megan Verlee

A student armed with a shotgun opened fire at a Colorado high school, Arapahoe County Sheriff Grayson Robinson said Friday. Police said the shooter injured two fellow students at Arapahoe High School in Centennial, Colo., before killing himself.

Investigators trying to unravel the murder of Colorado corrections chief Tom Clements seem to find many of the threads leading back to the 211 Crew. That's a white supremacist gang in Colorado's prisons. While a direct connection is still elusive, the evidence so far raises questions about the group, and the extent of their reach.

The head of Colorado's state prison system was shot and killed this week when he answered the front door at his home in Monument. The incident happened just hours before Colorado's governor signed strict new gun-control measures into law.