An appeals court on Wednesday ordered a Chicago police officer freed from prison in an Iowa assault case that has top brass back home defending one of their own.

The Iowa Court of Appeals said Officer Michael Mette's trial judge had no testimony on which to base her ruling that he could have walked away from a fight with another man — but didn't.

Mette had argued self-defense in the 2005 fight in Dubuque with Jake Gothard that left Gothard with a fractured nose, cheek and jaw.

In November 2006, 1st Judicial District Judge Monica Ackley found Mette guilty of assault causing serious injury and sentenced him to five years. She said Mette was not the initial aggressor but could have retreated.

The case prompted an outcry in Chicago, where prominent officials — including Chicago Mayor Richard Daley, Cook County State's Attorney Richard Devine and Chicago Police Superintendent Jody Weis — had called for Mette's release.

In its ruling, the appeals court found that there was no testimony to support Ackley's findings.