The Florida Supreme Court on Wednesday unanimously tossed out the death sentence of a man convicted in a 1994 murder in Duval County.

Justices found that an attorney for Michael Shellito, 37, failed to properly raise issues about the defendant's mental-health problems before Shellito was sentenced to Death Row. Justices sent the case back to a lower court for new sentencing proceedings.

Shellito was convicted in the shooting death of 18-year-old Sean Hathorne.  Shellito was 19 years old at the time of the crime.  He is now 37.

In the ruling, justices pointed to evidence suggesting that Shellito might have suffered from brain damage and possibly had been abused and neglected as a child.

Such "mitigation" evidence could have been used to try to prevent the imposition of the death penalty. But the Supreme Court said "our confidence in the outcome of the penalty proceeding is undermined" because of a "dearth" of mitigation evidence being presented.