LOS ANGELES (CNS) - A federal appeals court today overturned the conviction of Southland man found guilty of murder based largely on evidence detected by a police dog with a low success rate.

A three-judge panel of the U.S. 9th Circuit Court of Appeals in Pasadena ordered a Los Angeles federal judge to either release Gilbert Aguilar or grant him a new trial in the 2001 murder of John Guerrero.

According to the appellate panel, the prosecution's case largely hinged  on evidence that Reilly, a Los Angeles Police dog, had “alerted” to Aguilar's  scent on a stolen white Volkswagen that was found shortly after the murder.

Although Aguilar's fingerprints were not found in the car, Reilly's alert apparently confirmed the presence of the defendant's scent in the  passenger seat, leading to his conviction, according to the appeals court.

However, the panel determined the verdict was unfair because prosecutors had failed to reveal to the defense Reilly's long history of questionable results.

Aguilar was convicted in 2006 of first-degree murder and sentenced to 50 years to life in prison in the death of Guerrero in La Puente.

“Reilly's scent evidence was the only evidence at trial linking Aguilar  to the getaway car, as well as the only evidence corroborating strikingly  weak eyewitness identifications," according to the opinion.