HARRISBURG — The Pennsylvania Supreme Court justice who was convicted last month of using taxpayer-paid staff for political campaigns told the governor today she is resigning from the bench as of May 1, about a week before she will learn her sentence.

The letter from Justice Joan Orie Melvin to Gov. Tom Corbett said she made the decision “with deep regret and a broken heart.”

“It is my fervent hope that my service over the past three decades will not be tainted by the circumstances surrounding my departure,” wrote Melvin, who then listed accomplishments, including 8,000 decisions over 15 years and “respect for the taxpayers” shown by declining a pay raise and “consistently maintaining low office expenses.”

Melvin said in the letter she plans to appeal the jury’s verdict, which found her guilty of using government employees to work on her 2003 and 2009 campaigns for the high court. Her sentencing is May 7.

Melvin has been suspended without pay from the court since August. Her lawyers released the letter but did not respond to a message seeking a phone interview.

Melvin’s sister and aide, Janine Orie, also was convicted of misusing state-paid staffers to do campaign work. They were both found guilty of theft of services, conspiracy and misappropriation of state property. Melvin was acquitted of official oppression.

A third sister, former state Sen. Jane Orie, R-Allegheny, is serving 2 1/2 to 10 years in prison after a separate conviction on similar charges related to her own political campaigns.

The staunchly Republican, conservative Catholic sisters from Pittsburgh’s North Hills suburbs have argued the charges were overblown or outright lies whipped up by Allegheny County District Attorney Stephen Zappala Jr., a Democrat, allegedly because the Ories have opposed the expansion of legalized gambling, an industry in which Zappala’s relatives had an interest.