The photo, released by police after the boy disappeared on September 12, 2014, has a two-hour time difference between time stamps, The Australian has reported.
In an exclusive story, The Australian revealed that the currently halted inquest will now conduct an urgent forensic examination of the photograph.
The picture, which shows William playing on his foster grandmother’s veranda, was cited by counsel assisting the inquest as a “certain” in the timeline of William’s final hours.
In his opening address Gerard Craddock SC said the photograph was taken at 9.37am on the day in question, saying “that is a time of which we can be certain”.
Mr Craddock said “Nanna’s slippers” (the feet of the foster grandmother) placed William at that time on the veranda “whilst dressed as a Spider-Man he was actually a tiger. You can see him roaring”.
But a newly revealed document from the inquest’s brief of evidence, obtained by The Australian, says the jpeg photograph was “created” at 7.30am and “corrected” at 9.37am.
The report by X-Ways forensic software reads: “Created 12/09/2014 07:39:54 Corrected time: 12/09/2014 09:37:44”.
The photograph, regarded as “proof of life” that William was still alive at 9.37am, was a vital part of the timeline presented by Mr Craddock of William’s last known morning.
Until NSW Coroner Harriet Grahame’s urgently ordered forensic examination takes place, it is unclear if the time was corrected to 9.37am to cater for, say, the camera itself being set on the wrong time.
In Mr Craddock’s opening, he pins the timeline of William’s disappearance to the photo.
He says: “Five minutes seems to be about right” for the time William was out of his foster mother’s sight “taking into account the time of the last photo”.
If Mr Craddock’s opening statement is incorrect and the photograph was actually taken at 7.39am, the time of William’s disappearance may also alter.
A senior policewoman, Detective Sergeant Laura Beacroft told the inquest last month she put the time William vanished between 10.05am and 10.20am.
The foster mother called triple-0 at 10.56am to report him missing.
The Australian reported that an application to have the apparent time stamp discrepancy on the photo examined was made in court not long before the inquest was suddenly adjourned.
Ms Grahame and Mr Craddock agreed on the need for the forensic examination of the photograph.
The inquest into William Tyrrell’s disappearance will resume in March 2020.