PENSACOLA (Florida) - JURORS have convicted a karate instructor of killing a wealthy couple during a home invasion robbery while the couple's nine special-needs children cowered or slept nearby.

The Pensacola jury deliberated about five hours on Thursday before finding Patrick Gonzalez Jr guilty of two counts of first-degree murder and one count of home invasion robbery.

Prosecutors say he led the July 9, 2009, attack by a group of armed men that dressed as ninjas to attack Byrd and Melanie Billings.

Gonzalez is a 36-year-old father of six. He now faces a sentence of death or life in prison.

A safe taken from the family's home contained nothing of value, but a second safe that wasn't robbed had US$164,000 (S$212,693) in cash.

Ninja ringleader convicted