D and Stewart, wearing masks and carrying guns, robbed a bank. A security package containing a dye bomb designed to emit a red, tear-gas-like substance within minutes after removal was taken by the robbers. The Bank reported this to police, along with a general description of the robbers and their getaway car, and the opinion that a third person had been waiting outside. At trial, Brenda Jackson, Stewart's girlfriend, testified that D and Stewart had robbed the bank and that she was driving the getaway car when the dye bomb exploded, making it difficult for them to see. D switched places with Jackson and began driving. Stewart threw the shotgun out of the car and, after a bit, fled with the stolen money. A county deputy sheriff stopped D and Jackson and asked them to get out of the car. The deputy noticed a large red stain on the car's front seat, some gloves on the floorboard, and a white print shirt on the back seat, all in plain view through the car windows. D and Jackson were placed in the police car. Jackson asked the deputy, 'Why are you arresting us?' D immediately cut in, 'Shut up, you know why.' The stain was found to contain the same chemicals used in the bank's security packs. Stewart was apprehended a month later. Three months before trial, Jackson received a psychiatric examination and was judged competent to stand trial. She was also found to have used drugs intermittently. D's attorney was given access to the report, and the court granted his request for a preliminary examination into Jackson's current mental state. Jackson's answers to questions by government and defense attorneys were lucid and discriminating. The trial judge asked no questions, nor were expert witnesses employed. The judge declared Jackson competent to testify. She did and D was convicted. D appealed in part on the issue of the determination that Jackson was competent to testify.