Former Labour MP Margaret Moran fiddled her expenses claims to receive more than £53,000, a jury has ruled.
The 57-year-old claimed nearly her entire annual allowance in one bogus expenses entry and forged invoices for more than £20,000 of non-existent goods and services.
Moran, who served as MP for Luton South from 1997 until the 2010 election, was found to have falsely claimed around £60,000 in parliamentary expenses between 2004 and 2008, of which she received £53,000.
Jurors at Southwark Crown Court in London were unable to return a guilty verdict after it was ruled that Moran was unfit to stand trial for mental health reasons. Instead, in a trial of issue, the jury found she had committed 15 counts of false accounting and six counts of using a false instrument over the claims for parliamentary expenses.
Mr Justice Saunders adjourned the disposal of the case to a later date after the jury reached a unanimous verdict on all counts.
Moran may be subject to a supervision order, a hospital order or absolute discharge, where no further action is taken against her, the judge said. She will not face a criminal conviction due to her ill health which meant she was unfit to stand trial, the court heard.
"She is presently being treated by psychiatrists at home and that treatment will continue," Mr Justice Saunders said.
Moran's false expenses claims are the largest amount uncovered in the wake of the MPs' expenses scandal. Former Labour minister Elliot Morley was jailed last year for dishonestly claiming more than £30,000 in parliamentary expenses.
The court heard Moran submitted an invoice for £22,500 in August 2008 - just under the annual maximum expense allowance for an MP - to treat dry rot at her Southampton home, using the money instead to fund "home improvements". She was able to make the dry rot claim by "flipping" her two homes - changing which property was her second home and therefore allowing her to claim expenses on it.
Moran also changed dates on invoices for the work so that the money would be paid. One invoice in August 2007 was for £14,805 - apparently for boiler repairs and work on her conservatory in her constituency home in Luton, when it was actually at her house in Southampton, the court heard.