A federal grand jury added more charges Wednesday against two Egyptian college students accused of carrying illegal explosives in their car in South Carolina last year. Less than two weeks before their scheduled trial, federal prosecutors sought a new grand jury indictment charging former University of South Florida students Ahmed Abdellatif Sherif Mohamed, 26, and Youssef Samir Megahed, 21. The charges added include illegal possession of a destructive device and a count accusing Mohamed of supporting terrorism. Deputies in South Carolina who stopped their car Aug. 4 said they found items to build pipe bombs in the trunk. The men contend those items - PVC pipe containing a mixture of sugar, potassium nitrate and cat litter, plus fuses - were ingredients for homemade, low-grade fireworks. But also in the car, prosecutors say, was a laptop computer containing a video Mohamed made to demonstrate how to turn a remote-control toy into a detonator for a bomb.