The Indiana Supreme Court on Tuesday upheld a sentence of life without parole for a teenager who said he wanted to be like the fictional television serial killer Dexter a few weeks before strangling his 10-year-old brother.

Andrew Conley was 17 in November 2009 when he killed his brother, Conner, while wrestling in their home near Rising Sun and dumped the boy's body in a park. He unexpectedly pleaded guilty in September 2010, averting a murder trial.

In the 3-2 ruling, the justices said Conley acted "as if nothing was out of the ordinary" after the killing. According to testimony during the five-day sentencing hearing, Conley joked with his mother and watched football the day after he killed Conner.

Conley told police he fantasized about killing people since he was in eighth grade. A few weeks before the killing, Conley told his girlfriend that he wanted to be just like the TV serial killer as they walked on the trail where he later disposed of his brother's body.

Three different psychological experts who interviewed Conley all said he was seriously mentally ill, but his appellate lawyer, Leanna Weissmann, said the judge gave too much credence to a psychologist's testimony that the teen could be a psychopath.