A top Minnesota Corrections Department administrator who abruptly resigned Friday morning is facing an investigation by the agency after complaints about unspecified conduct.

The leadership shake-up prompted state Rep. Marion O'Neill, R-Maple Lake, to file a formal request for information regarding Deputy Commissioner Sarah Walker's time cards, calendar entries and electronic correspondence since her appointment in January.

The data request also asked for any open investigations concerning Walker, who resigned roughly six months after Commissioner Paul Schnell tapped her to lead the agency's community services division.

O'Neill pursued payroll data following concerns about Walker's job performance.

"How much was she actually doing DOC work for the past few weeks while she was still being paid?" said O'Neill, the minority lead on the House corrections subcommittee. "We're just doing our due diligence to get to the bottom of it."

In Walker's resignation letter, the former lobbyist on criminal justice issues indicated a desire to return to her advocacy work.

"In my short time as Deputy Commissioner, I have become convinced that my voice and skills are best suited for pushing for widespread reform from the outside," Walker wrote. "There are unique opportunities at the local and national level to advance significant reforms and reduce racial disparities and I feel compelled to contribute to those efforts without encumbrance."

A DOC spokeswoman said the department has received complaints about Walker, but "the investigation has not been completed." She declined to discuss the nature of those complaints.

The Minnesota Management and Budget agency confirmed that an outside investigator was retained June 26 to vet those complaints. They have yet to be billed for the services, said spokesman Chris Kelly.

In an interview with the Star Tribune, Walker described herself as an "easy target" because of her activism and denied knowledge of the data request — or the origin behind any grievances against her.

"I am proud of my time at the DOC and any allegations of wrongdoing are baseless and purely political," she said in a statement, denouncing accusations that she hasn't been working. "I welcome any investigation that is questioning my ethics."

Walker declined to comment on why she resigned but maintained that she left of her own volition.

In her time at the DOC, Walker used her public role to combat recidivism, while fostering long-term goals of reducing incarceration for low-level, nonviolent offenders and curtailing technical parole violations that can send former inmates back to prison.

Lofty criminal justice reforms like these have garnered interest, including from Minnesota's first lady. Gwen Walz, who has highlighted the "intersection of education and corrections" as a major focus at the DOC, encouraged Walker to apply for the deputy commissioner role.

A spokesman for Walz did not immediately respond to a request for comment.

Walker's exit comes after a week of staffing turnover and turmoil at the Department of Human Services. Commissioner Tony Lourey resigned abruptly on Monday, following the announced departure of two top agency aides. Gov. Tim Walz has tapped Pam Wheelock to serve as his replacement for the time being.

On Friday, Schnell accepted Walker's resignation, effective immediately.

Star Tribune reporters Torey Van Oot and Stephen Montemayor contributed to this report.