Law enforcement officials found a purchase receipt for one of the guns used in the assault among Cho's belongings.[202] The shooter waited one month after buying a Walther P22 pistol before he bought a second pistol, a Glock 19.[3]:24 Cho used a 15-round magazine in the Glock and a 10-round magazine in the Walther. The serial numbers on the weapons were filed off, but the ATF National Laboratory was able to reveal them and performed a firearms trace.[87]
The sale of firearms by licensed dealers in Virginia is restricted to residents who successfully pass a background check;[203] legal permanent resident aliens may purchase firearms.[204] At the time of the shooting, Virginia law also limited purchases of handguns to one every 30 days.[203] That limit was repealed on April 3, 2013.[205] Federal law requires a criminal background check for handgun purchases from licensed firearms dealers, and Virginia checks other databases in addition to the federally mandated NICS. A 1968 federal law passed in response to the assassinations of Robert F. Kennedy and Martin Luther King, Jr.[136] also prohibits those "adjudicated as a mental defective" from buying guns. This exclusion applied to Cho after a Virginia court declared him to be a danger to himself in late 2005 and sent him for psychiatric treatment.[15][206]:71 Because of gaps between federal and Virginia state laws, the state did not report Cho's legal status to the NICS.[15]
