The woman's lawyer Sharon Ramsden contacted detectives on Wednesday seeking confirmation that a brief of evidence had been sent to the DPP for the consideration of criminal proceedings against her client over the three-year-old's disappearance.
She was responding to reports on Tuesday that police had recommended William's foster mother be prosecuted over his disappearance in 2014.
"The foster mother and her legal representatives call for disclosure of the evidence which police suggest forms the basis of any criminal proceedings," a statement released by her lawyers said.
"The foster mother has always, and maintains, she has nothing to do with William's disappearance."
The police case allegedly says the woman, who cannot be named for legal reasons, might have disposed of William's body following a fatal accident at a property in Kendall, on the NSW mid-north coast.
Police have recommended she be charged with perverting the course of justice and interfering with a corpse, multiple media outlets reported.
A brief of evidence has reportedly been handed to the DPP but no decision has been made on whether charges will be laid.
The statement from the woman's lawyer stressed the foster mother had previously been ruled out of any wrongdoing in relation to his disappearance.
"William's foster mother and her legal representatives urge the Director of Public Prosecutions to expeditiously determine whether charges are to be laid," the statement said.
The woman, who is in her late 50s, was acquitted last year of lying to the NSW Crime Commission about hitting a different child with a wooden spoon.
The charge was unrelated to William's disappearance, which has been the subject of sustained efforts by police to find answers.
The case of the boy who went missing in a Spider-Man suit has gripped the nation for nearly nine years.
During a court hearing last November over the lying charge, a senior NSW detective said he believed the woman had knowledge of William's whereabouts.
"I have formed the view (she) knows where William Tyrrell is," Detective Sergeant Andrew Lonergan told Downing Centre Local Court at the time.
The woman's barrister, John Stratton SC, suggested police had charged her for allegedly lying in an attempt to pressure her.
"You are hoping to break her spirit," Mr Stratton said.
"Our main objective is to find out where William Tyrrell is," Det Sgt Lonergan said.
In December 2020, a highly-publicised month-long search of the Kendall property and surrounding area failed to find any trace of the boy.
Police dug up a garden at the property, which belonged to William's foster grandmother, and examined a concrete slab laid after his disappearance.
They also drained a nearby creek and sifted through soil in bushland and around the home.
A $1 million reward for information leading to the recovery of William and the circumstances surrounding his disappearance was announced in 2016.
The Office of the Director of Public Prosecutions declined to comment on the reports.
NSW Police said: "There are no updates in relation to this matter. The investigation is ongoing".