usher033010_01_X17crop230.jpg A family friend of Usher is being investigated for the jet ski accident that left the Grammy winner's stepson with Tameka Foster brain dead.

Jeffrey S. Hubbard, 38, was riding a jet ski that collided with 11-year-old Kyle Glover and a female friend on Georgia's Lake Lanier on July 8, causing the pre-teen to be airlifted to an Atlanta hospital, where he currently remains on life support. The children were being pulled in an inner tube when Hubbard lost control of his craft and struck Glover in the head. The boy was unresponsive and face up in the water by the time rescue department rangers reached him.

"The accident is under investigation, and Hubbard is [under investigation] as the operator of the personal watercraft," Sgt. Mike Burgamy of the Georgia Department of Natural Resources told ABC News. Officials said neither drugs nor alcohol are suspected in the tragic accident. No word on whether the family will chose to keep their son on life support.

Still dealing with the tragedy, Usher has pulled out as a presenter at tonight's ESPY awards.