A landmark ruling that undermined the scientific basis of the technique police use to match bullets to a gun is becoming a bane for prosecutors.

The Oregon Court of Appeals cited a May ruling that toolmark analysis is not “scientific evidence” when it overturned the second-degree murder conviction of Reza Mardani last week.

Mardani, a landlord in Northeast Portland, is accused of killing two tenants he had tried to evict because he believed they were engaged in illicit behavior. He’s been in custody since 2019.

“I’m thrilled to be able to clarify how ballistics comparisons are used in trials,” said Alicia Hercher, who represented Mardani during the original criminal trial.

Forensic examiners have long maintained that the grooves on firearm barrels leave unique markings on shell cas

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