Detectives investigating the disappearance of William Tyrrell have asked prosecutors to suspend their inquiry into the toddler's former foster mother until after the coronial inquest resumes.

NSW Police handed a brief of evidence to the Director of Public Prosecution (DPP) last year, seeking advice about whether there was enough evidence to charge William's former foster mother over his disappearance.

The DPP have released a statement this week saying NSW Police asked the office to "suspend its consideration" of the case until after the next set of hearings resumes in December.

Prosecutors were originally set to decide on whether there was enough evidence to charge the foster mother earlier this year, but had not made a decision before the inquest was scheduled to resume in March, pushing the next set of hearings back again until the end of the year.

The foster mother's lawyer has declined to comment on the decision to suspend the DPP inquiry, but told the ABC late last year she urged prosecutors to "expeditiously determine" whether the foster mother would be charged.

"The foster mother and her legal representatives call for disclosure of the evidence which police suggest forms the basis of any criminal proceedings," the statement said.

"She desperately urges the police to resume the investigation into finding out what happened to William."

In October 2020, at the end of the last set of hearings, a police strike force shifted its focus back to William's former foster mother, conducting searches of the property in Kendall and surrounding areas.

That search lasted several weeks, but nothing significant was found.

William's former foster mother, who cannot legally be identified, has always denied any knowledge of what happened to the boy.

The foster parents were also questioned at the NSW Crime Commission about the case, where people can be legally compelled to testify truthfully, before they were both charged with lying at the hearing.