ST. CHARLES – An Algonquin teen who shot and killed his father in 2010 has been sentenced to 18 years in prison after pleading guilty but mentally ill to second-degree murder.

David W. Szalonek, now 19, was 16 when he shot 51-year-old Brian Szalonek in the head with a shotgun on Feb. 8, 2010, in their home on Westbourne Parkway. The plea deal was accepted Wednesday in Kane County Court by Judge James Hallock.

A psychiatrist diagnosed David Szalonek with Asperger’s syndrome, which is a form of autism, and depression. About six months before the shooting, Szalonek had been hospitalized in a psychiatric facility.