The grand jury began its work last week, more than two months after the shooting.
Federal authorities said a grand jury began hearing evidence in the case last fall.
He said the grand jury began its investigation after problems with the program were brought to light by county officials.
In the morning of August 10, 2006, the jury began deliberations.
By early summer, federal investigators had taken control of the case and a grand jury began looking into Davis' behavior.
Officials said a grand jury could begin to hear evidence within a month.
The second grand jury began investigating the case last week.
On Sept. 15, a grand jury began hearing evidence in the case.
The jury began to consider their verdict on 29 May 2009.
The jury began deliberating and went home after half an hour.