Alexa Bartell, 20 (Provided by Jefferson County Sheriff’s Department) A second teenage suspect pleaded guilty to murder charges Wednesday for his role in a spree of Jefferson County rock-throwing attacks that targeted seven drivers and killed 20-year-old Alexa Bartell last year. Nicholas Karol-Chik, 19, pleaded guilty to second-degree murder, criminal attempt to commit first-degree murder and a crime of violence sentence enhancer as part of a plea agreement during a disposition hearing in First Judicial District Court Wednesday. As part of the plea deal, prosecutors dismissed the original 15 charges, including multiple counts of first-degree murder and assault. In a sentencing addendum, prosecutors and the defense agreed to a minimum sentence of 35 years in the Department of Corrections for the charge of second-degree murder and a maximum prison sentence of 48 years on that charge. The general sentencing range for second-degree murder is between 16 and 48 years. Karol-Chik also faces an additional eight to 24 years in prison for the charge of criminal attempt to commit first-degree murder. In total, the teen could face up to 72 years in prison and will not be sentenced to the Youthful Offender System — a medium-security prison in Pueblo that houses male and female offenders between ages the ages of 14 and 19 — First Judicial District Judge Christopher Zenisek said during Wednesday’s hearing. A sentencing hearing has been set for Sept.