The person hand-picked by Atlanta Mayor Keisha Lance Bottoms to oversee the city's beleaguered federal grants programs resigned suddenly Monday, after less than four months on the job.

P. Nigel Roberts' departure from City Hall is effective Thursday. The city's management of grants has been the subject two federal investigations, including one by the U.S. Department of Housing and Urban Development that found chronic mismanagement of a program that subsidizes rent for people living with AIDS.

Roberts’ announcement comes just three weeks after his director of planning and operations stepped down, accusing top city officials of bullying and intimidating employees who refused to comply with unlawful orders.

On the same day Bottoms announced Roberts' hiring in February, the city received a letter from HUD threatening to terminate the city's $23 million Housing Opportunities to People With AIDS (HOPWA) grant.

Atlanta City Council members received an unsigned announcement from Roberts’ department late Monday. It said that Roberts — who has 27 years of experience working in city, county, state, not-for-profit and private organizations administering HUD Entitlement Funds— has decided not to relocate his family from Birmingham, Alabama.

“He has informed us that the distance and time required to do the job well has created a hardship for his family,” the announcement said.

Some council members had expressed hope that Roberts could turn around the city’s grant situation.

But a blistering resignation letter dated May 4 from Christina Cummings, the department’s former director of planning and operations, alleged that the problems with city’s federal grants were much worse than previously known.

Cummings accused the city of misappropriating federal funds, interfering with the procurement process and steering federal grant money to politically-connected contractors.

Cummings had only been in her position for about six months.

In her letter, Cummings said the city had “hundreds of millions of dollars in federal funds.”

“Those dollars are intended to help elevate the lives of the poor and most medically fragile residents,” Cummings wrote.

On Tuesday, the Bottoms’ administration declined to make Roberts available for an interview.

In a statement, a Bottoms’ spokesman disputed Cummings allegations.

“While there are numerous factually inaccurate and false statements within the resignation letter, we will let the facts of the matter guide our process in bolstering this critical program,” it said.

The city disperses HOPWA funds to several non-profits who help secure housing for 2,300 household’s in 29 Atlanta metro area counties. But the city has often delayed payments of grant funds to the agencies, forcing them to obtain lines of credit to avoid evictions.

The February HUD letter imposes strict guidelines on how the city spends this year’s award and threatens to terminate the city’s participation in the program if it violates the conditions.

Earlier this month, five of Georgia's leading advocates for people living with HIV/AIDS recently called for the program to be placed under state control.