The Hawaii Supreme Court set aside a man’s manslaughter conviction Friday for the 2009 beating of his estranged wife’s boyfriend with a 2-foot-long metal reinforcing bar.

The high court ruled that Circuit Judge Karen Ahn should have permitted the jury to consider the lesser offense of first-degree assault.

The justices sent the case back to Circuit Court for a new trial for Paul C.K. Kaeo.

Kaeo, 49, went on trial on a charge of murdering Charles Kahu­moku Jr. Kahu­moku, 49, died from head injuries in the May 8, 2009, beating in Maili.

The jury returned a verdict convicting Kaeo of the lesser manslaughter charge of recklessly killing Kahu­­moku. Kaeo received a sentence of six to 20 years in prison.

In the appeal, Kaeo’s lawyers said the judge should have granted the defense request of allowing the jurors the option of returning a verdict on the lesser offense of first-degree assault, which carries a maximum 10-year term.

The high court agreed.

The new trial would be on the charge of manslaughter.

Murder carries a mandatory life term with parole.