CHICAGO (CBS) — An Elgin man was sentenced to 55 years in prison Friday for the shooting death of a 20-year-old in 2015.

William M. Ingram, 32, was found guilty in September in the first-degree murder of Devonte Turner.

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(Credit: Kane County State’s Attorney’s Office)

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Kane County prosecutors presented evidence that Turner was sitting in the front passenger’s seat of his friend’s car on Elgin’s west side in April 2015 when he was shot. Prosecutors said Ingram snuck up behind the car as Turner’s friend was driving and fired seven shots at Turner through the rear window, striking him in the back of the head.

Turner’s friend off drove for help and Turner later died at a hospital. Prosecutors believe Turner was mistaken for someone else.

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Kane County Associate Judge Charles E. Peterson sentenced Ingram to 30 years for murder, along with a mandatory 25 years because Ingram fired the gun used to kill Turner. He is already serving a 15-year sentence for a 2014 drug offense, after which he will begin serving the murder sentence.