The assistant attorney general who told state corrections officials in 2012 they didn’t need to manually recalculate prisoners’ sentences after discovery of a software error that allowed thousands of prisoners to get out early is quitting.

Attorney General Bob Ferguson said Thursday that he had received a resignation letter from Assistant Attorney General Ronda Larson. She will leave at the end of the month, he said.

Ferguson disclosed the resignation to a gathering of newspaper editors and publishers at the Capitol.

Ferguson, in a brief interview, said he accepted the letter but wouldn’t elaborate on whether he had asked her to step down.

“It’s a personnel matter. We just don’t talk about personnel matters,” he said.

Between 2002 and December 2015, as many as 3,700 inmates were released from prison early because their sentences had been wrongly calculated. Officials with the Department of Corrections have attributed the error to an incorrect algorithm in the software used to determine the release dates.

The problem came to light in 2012. At that time, corrections officials sought advice on how to proceed until a fix was made.

Larson, in a Dec. 7, 2012 email, wrote “I don’t believe it is necessary, from a risk management perspective, to do hand calculations now of everyone in prison with an enhancement.”

She said waiting for the system to be reprogrammed “should be sufficient.”

Ferguson has since deemed that advice as flawed and launched an internal probe of his agency’s involvement in the mistaken release of inmates. He told editors and publishers that investigation is still under way.