A disabled man who was strip searched after a false claim he had photographed schoolchildren should receive an apology and have his conviction expunged, a report has found.

But Western Australia's attorney general says the government won't compensate Denys Martin who was arrested in Cottesloe in 2017 on suspicion of possessing child exploitation material.

Mr Martin was forcibly fingerprinted in an unsuccessful bid to identify him and later fined $500 plus costs of $190 for failing to provide his details.

Parliamentary inspector to the Corruption and Crime Commission Michael Murray was critical of the WA Police Force and the CCC over the incident.

In his report tabled in parliament on Thursday, Mr Murray said it seemed Mr Martin was pretending to photograph cars that appeared to exceed the speed limit perhaps as a warning, but did not have a camera on him.

Mr Murray said Mr Martin had done nothing wrong and should not have been prosecuted.

"Mr Martin should not have been arrested and there was no basis to require him to provide his personal details," he said.

The inspector recommended the executive council pardon Mr Martin, that his fine and costs be repaid, and an apology given.

But Attorney General John Quigley said he would not intervene because Mr Martin had pleaded guilty.

"I don't think the state's got any scope to act once the citizen goes to court and pleads guilty to an offence," he told reporters.

"How can the state then get in there and give compensation or rectification?"

In his report, Mr Murray said after police initially largely dismissed Mr Martin's mistreatment complaint, a senior police solicitor recommended he be given an apology and assistance to appeal his conviction.

But police received independent legal advice and decided the arrest was lawful.

The CCC found in January 2018 that there were no grounds to form an opinion of serious police misconduct.

It was only after a complaint was lodged with the parliamentary inspector that the CCC reinvestigated.

The CCC commissioner advised while he did not disagree with the inspector, the issue was beyond the CCC's functions.

The inspector said Mr Martin had "suffered an injustice for which no remedy has been provided" and that this in "itself demonstrates the ineffectiveness" of the CCC's review process.