The Newtown killer (forgot his name and it is not something worth remembering so I won't look up) was a law abiding citizen just before he killed his mother, another law abiding citizen who happened to have lots of gun, which according to many is the way to live a secure life in USA. Then he went on a rampage already an armed criminal. In short, I think the criminals do not have problems getting the guns for the law abiding citizens already have an easy access to them.

Adam Lanza became a criminal because he was mentally ill. Personally, I think that his mother was irresponsible, to say the least, to keep so many guns in a house occupied by a mentally unbalanced individual. From what I hear, she was also somewhat mentally unbalanced - apparently she had all those guns because she was a survivalist.

However, if you really believe that criminals get their guns from law abiding citizens, perhaps you should get your head examined.