Mayor Dwight C. Jones once considered Byron C. Marshall indispensable to his administration.

For at least three years, the mayor quietly showered Mr. Marshall with thousands of dollars in bonuses as a reward for his work in managing City Hall as chief administrative officer. Mayor Jones also doubled Mr. Marshall’s deferred compensation for retirement and provided other perks to keep him from being wooed away by another locality.

But somehow the mutual respect and trust between them eroded in recent months.

In an unexpected move, Mayor Jones, who has a little more than two years left in office, abruptly ousted Mr. Marshall, the No. 2 official at City Hall.

On Monday, the mayor simply announced he had accepted Mr. Marshall’s “resignation” and wished him well.

Mr. Marshall, 63, could not be reached for comment, though he has told others that he is not unhappy about leaving the City Hall pressure cooker and had no trouble accepting his ouster because he served at the pleasure of the mayor.

What he will do next is unknown. He is due a severance package worth more than $105,000.

Leaving an office in Richmond is not a career-breaker. Harry Black, a former chief financial officer who battled with City Council, has gone on to serve as chief financial officer in Baltimore and just became the city manager of Cincinnati.

How much impact Mr. Marshall’s departure will have is uncertain. As CAO, Mr. Marshall had his finger in every pie at City Hall in his role as the final decision-maker for the administration. He held sway over hiring and firing and had to approve all contracts.

Still, for most city residents, the change at the top is mostly a curiosity with little impact on daily life. Police are still patrolling, trash is being picked up and other operations are continuing without interruption.

As the mayor put it, “We have a capable team in place — many of whom have been with me since the beginning — and we are moving forward without interruption.”

The mayor named Christopher L. Beschler, the city’s chief operating officer, as interim CAO with full authority to hire and fire employees, sign contracts and take other actions on behalf of the city. Mr. Beschler also served as acting CAO during the final year of former Mayor L. Douglas Wilder’s administration.

City Council must confirm the interim CAO’s appointment. A special meeting will be held 8:30 a.m. Friday to confirm Mr. Beschler’s appointment.

Mr. Marshall’s departure gained interest when the mayor did not issue any explanation for the resignation. He apparently briefed some council members, but only after demanding each sign a confidentiality agreement in a bid to prevent leaks — a first for City Hall. The mayor even brought in an outside legal expert on such matters to craft the agreement. Five council members signed, while four did not.

The four council members who did not sign were Jonathan T. Baliles, 1st District; Chris A. Hilbert, 3rd District; Parker C. Agelasto, 5th District; and Reva M. Trammell, 8th District.