The Kansas Supreme Court has unanimously overturned the conviction of a man who killed an insect exterminator in February 2008.

The court ruled Friday the case against 61-year-old Howard Barrett should be returned to Riley County for a new trial.

Barrett beat and fatally stabbed 48-year-old Thomas James, who was doing extermination work in Barrett's apartment in Leonardville.

His attorney argued that Barrett, who is schizophrenic, felt irrationally threatened by James.

Barrett was convicted in November 2014 of second-degree murder but appealed, saying jurors should have been instructed they could find him guilty of imperfect self-defense voluntary manslaughter.

The Court of Appeals ruled that error was harmless because Barrett's second-degree murder conviction nullified a possible manslaughter conviction.

The Supreme Court disagreed, saying the jury could have reasonably convicted Barrett of manslaughter.