An employee of Roanoke Firearms, where Cho purchased his weapon, told ABC news that Cho "answered no" to the question regarding his mental history. Under state law he told the truth, but under federal law he lied.
Even though Seung-Hui Cho was detained for two days in a mental institution, ordered by a Virginia judge to undergo outpatient treatment and labeled "a danger to himself," he checked "No" when asked if he'd ever been adjudicated mentally defective or committed to a mental institution on the application to purchase the 9 mm handgun used in the massacre at Virginia Tech.
Ironically, under Virginia's lax gun laws even a person who has been determined by a court to be a danger to himself and ordered to undergo outpatient treatment can buy a gun.
The judge who issued the order was not required to enter Cho into a state database to raise any red flags. Judge Paul Barnett, who signed the order, told ABC News he didn't have to report Cho to state authorities because he did not determine that Cho needed inpatient treatment.
Donna Tate, the program manager for the Virginia State Police, told ABC News that Virginia enforces both state and federal gun laws and has its own database, but does not participate in the federal database because its state database covers both. Tate wouldn't comment on Cho's specific case because it is "an open criminal investigation."
Federal requirements are stricter than Virginia's, and the criteria used to determine whether or not a person has been declared mentally incompetent is broader. Cho's order would have been flagged under federal background check gun laws, but not in Virginia, according to Josh Horowitz of the Coalition to Stop Gun Violence.
"It's a criminal check only," says Horowitz. "Under federal law, there's 10 prohibited categories, including addicted to a controlled substance, immigration status, mental incapacity."
Horowitz calls Virginia's background checks "instant." "There's no registration requirement; there's no enhanced background check; there's no waiting period," he said.
Virginia only requires that potential gun buyer be 21 if purchasing from a licensed handgun store and have no criminal record.
"There's other states who have some transparency in their gun sales. Virginia has none of that," says Horowitz. "Virginia is 'let's sell it to somebody and let's not find out anything about them.'"
Ellen Davis contributed to this report.