Western Australia's Police Commissioner says an internal review is underway to determine how the trial of two alleged gold thieves was abandoned before it could begin due to a forensics "error". 

Shane Steven Hodgson, 50, and 34-year-old Joshua Luke Cross walked free from the Kalgoorlie Magistrate's Court on Friday with all charges dismissed while the pair were also awarded a combined $22,036 in court costs.

The court was told the laboratory that WA Police used for a process known as gold fingerprinting, Perth-based Source Certain International, analysed the wrong material. 

WA Police asked for an adjournment to re-test the material, but a two-day trial that was due to begin this week was instead vacated and the charges dismissed.

Police review underway

Speaking on ABC Radio Perth on Wednesday, Mr Blanch said a review of the case had begun, and said: "We're very disappointed obviously with that outcome."

"We are doing a review about the issue with forensics," Mr Blanch told ABC presenter Nadia Mitsopoulos.   

"We did ask the court if we could have an extension because of the error. 

"The court wasn't prepared to give us that extension and basically threw the case out of court. 

"We accept the position of the court, but we must review it because we rely heavily on external parties to do forensic testing for us.  

"If there's a mistake or an error, which we've seen in the past around the country, it can be fatal to court cases, so we've just started a review on that. 

In response to the Police Commissioner's comments, the ABC contacted Source Certain International and was issued a statement.  

"We do not comment on active investigations and, as this is subject to review, it would also not be appropriate for us to make a comment at this time," the company's CEO Cameron Scadding said in a statement.  

"We will support WA Police in the review of this investigation. 

"Our company and technical experts have a strong track record of supporting forensic investigations like this one and we will continue to assist WA Police with any further requirements." 

Defence critical of police

The court heard it was noted in the police running sheet — a formal document that keeps track of dates and progress of investigations — that the draft report of the laboratory analysis was received by detectives from the Kalgoorlie-based Gold Stealing Detection Unit on March 18 this year.

The document also noted on July 1, seven weeks before the trial was due to start, that police asked to test gold samples from Carosue Dam against the material found in a car belonging to one of the accused. 

Police prosecutor Senior Constable Matthew Fullgrabe told the court about the forensics error. 

"Officers were under the impression that the analysis was completed," he said.

"It was not until July that they realised the wrong material had been analysed."

Defence lawyer Paul Holmes, who was acting for Mr Hodgson, argued in court that further delays would result in a "serious injustice" and "undermine public confidence in the justice system". 

Both Mr Holmes and Mr Cross's defence lawyer, Ashley Watson, were critical of WA Police's handling of the case.  

"These are detectives in the gold squad," Mr Watson told the court. 

"I don't want to be rude, but it's not just uniformed police … these are experienced detectives." 

In making her ruling last week, Magistrate Janie Gibbs said there was no explanation from police for the four-month delay where "they had the opportunity to get further samples."

She said she initially believed police were not at fault and that it was an "oversight". 

"But I don't think that position can be maintained," she said.