Joseph Yacteen, 27, pleaded guilty in July to attempted first-degree murder. He was accused of firing a gun into a van carrying Cohn's band in a Denver parking garage in August 2005.
The bullet grazed driver-tour manager Thomas Dube before it lodged in Cohn's temple. Both were treated and released from a hospital the next day.
Police said Yacteen tried to steal the van and then forced four men out of another vehicle nearby. He was later found in a vacant house where police forced him out with tear gas after a standoff of nearly six hours.
Prosecutors dropped charges of second-degree assault, aggravated robbery, attempted aggravated robbery, menacing and first-degree criminal trespass, all felonies.
Patricia Vail, 23, is a accused of helping Yacteen and faces a felony accessory charge.