D.C. Mayor Vincent Gray said Tuesday that the District's chief financial officer should rework how his office conducts employee background checks, bringing new heft to a long-standing criticism of an agency that once drew attention for an employee's $48 million theft.

At a meeting with Gray and city lawmakers, Natwar Gandhi said his office's pre-employment review includes salary verification, Internet searches and ensuring the applicant is current on their District taxes.

Only after a person is hired, Gandhi said, do city officials check criminal histories, education records, credit reports, references and federal tax filings. Gandhi said his office's protocols are similar to those the federal government uses.

But Gandhi's strategy still left Gray concerned.

"Maybe some of those things should come before rather than after an offer has been made," said Gray, who added he was most interested in seeing Gandhi's office review applicants' federal tax records before hiring.

David Umansky, Gandhi's spokesman, said the office was "immediately going to review all of our processes to see what changes should and can be made."

Gandhi has faced renewed questions about his office's screening practices after a series of Washington Post reports about the city's chief tax appraiser prompted several legislators to seek more information about his vetting.

But questions about Gandhi's employment-linked investigations have been a mainstay of Gandhi's 12-year tenure.

Soon after Gandhi took over as CFO, his general counsel resigned after an internal probe found that "he held neither a law degree nor a license to practice law."

The criticisms resurfaced after Harriette Walters, an Office of Tax and Revenue employee, was arrested in 2007 for stealing more than $48 million during nearly two decades in government. Walters is now serving a 17 1/2-year prison sentence.

About eight months before a judge sentenced Walters, the D.C. auditor found fault in Gandhi's screenings and warned the lack of pre-employment background checks could expose the city to "an unreasonable risk of financial harm from misappropriation and other fraudulent activities."

At the time, a Gandhi aide defended the office's procedures.

"The investigations can take months to complete," Robert Andary, the executive director of Gandhi's integrity and oversight office, told auditors. "It would not be practical to conduct this type of investigation on applicants and to expect most applicants to be willing to wait for the results of a background investigation before being hired."