A request for comment from Chief Financial Officer Natwar M. Gandhi, who oversees the D.C. tax office, was not returned Thursday.
This year, DiVello’s office completed an audit critical of the city’s assessment procedures. The audit concluded that the tax office employed a “significantly flawed” computer database made vulnerable by office managers who could change assessed property values without detection.
The audit was made public after The Washington Post obtained a copy and wrote about its findings in August.
The council will hold a hearing Wednesday on how assessments are conducted.
DiVello, whose resignation was effective immediately, had been expected to brief council members Thursday in advance of the hearing.
But he resigned after a heated meeting with the Office of the Chief Financial Officer’s general counsel and director of operations over what to present at the council hearing, according to two people with knowledge of the meeting who spoke on the condition of anonymity to speak freely about Thursday’s events.
Council member Jack Evans (D-Ward 2), who scheduled next week’s hearing, said he was told that DiVello resigned after refusing to agree with the office that his team made a mistake when it concluded changes to the database were not detectable.
“The question is, ‘Where does the truth lie?’ ” Evans said. “From my perspective, we should call this guy” to testify.
DiVello’s team updated the audit to respond to questions from council members and reviewed recommendations with the tax office. The audit was then formally submitted.
Council members, who have demanded more information about the database, received the final revised audit this week. The tax office has promised to implement several changes to strengthen internal controls by Nov. 1.
DiVello, 65, is a certified inspector and fraud investigator, according to his biography on the city government’s Web site. He previously oversaw citywide financial audits as an assistant inspector general in the Office of the Inspector General.
The internal affairs unit is responsible for reviewing the operations of the Office of the Chief Financial Officer, investigating alleged violations by employees and performing background checks on employees and contractors, according the site.
An anonymous complaint from a staff tax office employee prompted the internal affairs unit and the FBI to investigate reductions in property assessments through settlements by the tax office, several people with knowledge of the probes have told The Post.
The Post found that the tax office lowered the proposed taxable value on 500 commercial properties by a total of $2.6 billion this year through the settlements.
The Post also found that chief appraiser Tony L. George was terminated from a previous job in Fulton County, Ga., after complaints about how assessments had been lowered. He did not disclose the termination on his D.C. job application.
Jennifer Jenkins contributed to this report.