BOSTON (WHDH) -- The state has confirmed it will challenge a federal judge's decision to allow a convicted killer to undergo a taxpayer-funded sex change operation.

The judge made the ruling in favor of Michelle Kosilek earlier this month.

The judge's ruling sparked outrage across the state -- and now the state of Massachusetts is taking action. It will appeal the ruling that taxpayers must foot the bill for a sex change operation for Michelle Kosilek.

She was born as Robert Kosilek, and was convicted of murdering his wife back in 1990.

A judge ruled the surgery was necessary to care for Kosilek's gender identity disorder.