Then further investigations revealed she'd actually stolen nearly 10 times that amount.
The 65-year-old pleaded guilty on Thursday to stealing and dishonestly obtaining more than $430,000 from her employer over nearly a decade.
The amount is not insignificant and the duration of her crime was protracted, her barrister Hayden Rattray said, conceding prison was the only sentence that could be imposed.
None of the money has been repaid to Melbourne High School.
Walshe was first employed as an assistant bursar at the school in 1994 and after a period was promoted to business manager.
Prosecutor Lauren Gurry revealed Walshe had full access to all the school's bank accounts and, because of administrative oversight, worked with single tier authorisation allowing her to make payments and transfers without anyone else knowing or approving them.
On 254 occasions between January 2012 and September 2021 Walshe transferred funds from the school bank accounts to her own personal bank account.
Account statements found in her office revealed originals with white-out concealing her account details, and copies which because of the white-out did not include that information.
On another 10 occasions she altered payee details on invoices sent by the school, so funds were paid into her account.
M Rattray acknowledged the offending was not sophisticated.
Walshe knew structural and governance issues meant her offending was unlikely to be uncovered, he said.
The thefts were uncovered after newly appointed principal Tony Mordini set out to address the education department's concerns about potential poor financial governance.Â
Walshe was dismissive of concerns when questioned by him and claimed processes were designed to make his job easier, Ms Gurry said.
In November 2021 he met with Walshe and department staff, confronting her about what was then believed to be the theft of $47,000.
Walshe resigned and apologised "for the "grief I've caused both you and the school". She blamed a gambling problem for the thefts.
A later audit revealed she had stolen $432,546.88 from the school. Nothing has been repaid.
"Plainly my client was trusted at the school ... she gained a great deal of self-worth from her role at that school," Mr Rattray said.
She was proud of her job and for a long time, outside the local pokies venue, it was the only community she was part of, he said.
Walshe turned to gambling after the abrupt end of her second marriage, when her husband met another woman on a trip to the Philippines.
She had dabbled in gambling previously but gravitated toward the pokies venue opposite her home as a source of solace and community, Mr Rattray said.
Walshe feels shame and guilt about the gambling and theft and was surprised by the total amount, he said.
She will be sentenced by County Court Judge Peter Lauritsen.
