Cleveland.com reports Lane was sentenced to three life sentences without parole for killing Daniel Parmertor, 16; Demetrius Hewlin, 16; and Russell King Jr., 17.
According to video footage from the courtroom, the 18-year-old was seen "smirking and smiling" while family members of the victims made statements to the court. At one point he gave a statement in which he cursed and gave the middle finger to the court.
On February 26, almost one year after the shooting, Lane pleaded guilty to three counts of aggravated murder, two counts of attempted aggravated murder and one count of felonious assault.
Last year Lane filed a plea of not guilty by reason of insanity.
Video footage from the day Lane opened fire at the school's cafeteria and was arrested, shows the teen wearing a grey shirt with the word "killer" written across his chest, just like the one he donned on Tuesday's trial, the Atlantic Wire reported.
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