[Zon]

If this is so, why did he obliterate the serial numbers on his weapons?

Did he file off the serial numbers? Without the serial numbers there's no way to trace the guns to a specific gun dealer and purchaser. What if the guns used in the shooting were obtained illegally and had been used in other crimes before Cho came into their possession? Would law enforcement be able to trace the bullets to previous killings or crimes? Perhaps the package that NBC received documents those other crimes. 

I'm out on a limb here. But ever since the serial numbers being filed off and the gun receipt were reported I've pondered the history of the guns. Also, if Cho filed off the numbers and intentionally put the gun receipt in the backpack what was he up to? Was it a message?

If the guns Cho used were not the guns he recently purchased from the licensed gun dealer where are they? Perhaps they'll be found latter having been used to commit a crime and traced back to Cho. Perhaps ballistics from the VT crime scene bullets show that there were three guns used by Cho that day.

If this has any merit it's unlikely that it'll be reported in the news. Pondering the history of the guns and what Cho was up to with them I realized a seemingly endless supply of "what ifs?".

[CindyDawg]

JAT but I think he probably filed them off because at the time he might have thought he could get away with this.

[AUsome Joy]

I know nothing about guns, but I thought I heard the comment on TV yesterday that the FBI or other authorities, had a way to raise the serial numbers.

[Atlas Sneezed]

Did he file off the serial numbers? Without the serial numbers there’s no way to trace the guns to a specific gun dealer and purchaser. What if the guns used in the shooting were obtained illegally and had been used in other crimes before Cho came into their possession? Would law enforcement be able to trace the bullets to previous killings or crimes? Perhaps the package that NBC received documents those other crimes.

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He probably used one of the Dremal tools found among his things.

And it is quite easy to recover a ground-off serial number, because the stamping process distorts the metal even below the surface. Most morons just remove enough material until they see flat metal, and stop. One then polishes that surface, smoothing it if needed, and uses acid to reveal the number. If you stipple or stamp the number first to obliterate it with more sever distortion that the numbers were stamped with, then grind away, they probably won’t be able to recover the number.

No way to trace the bullets. Only on TV.