The grand jury, set to convene Tuesday, was "previously scheduled by the former prosecutor," said the statement from Corey.
"The decision should not be considered a factor in the final determination of the case," her office said.
Corey said the investigation into the case continues. The state attorney has maintained that a grand jury is not needed to file possible criminal charges against George Zimmerman, the neighborhood watch volunteer who killed the teen February 26.
The case has triggered a nationwide debate about Florida's "stand your ground" law -- which allows people to use deadly force anywhere they feel a reasonable threat of death or serious injury -- and race in America.