I doubt an ME could tell the difference between .223 and 5.56 wound, and not many could tell the brass without very close examination.
Police and FBI should be able to tell the difference between .223 and 5.56, don’t you think???
http://abcnews.go.com/blogs/headlines/2012/12/live-updates-newtown-conn-school-shooting/
So we have a poster on this site claiming an EMS person said they were 5.56 and a reporter claiming law enforcement said they were .223
Video I came across that is interesting. Especially the early part on rifles.
WARNING - graphic in spots. First graphic picture is probably the worst and it is after the 8 minute mark.
https://www.youtube.com/watch?v=tku8YI68-JA
What is interesting is the wounds that rifles make vs. handguns. Also that the .223 fragmenting bullet may not start its devastating cavitation actions early enough in a small body and may still pass through due to the velocity. See at 7:05.
As for the powerful assault rifle .223 listen to the doctors comments at 7:34. ‘This is a very small caliber. This is one of the reason the military is looking at larger caliber ammunition’. So much for the powerful .223 ‘assault rifle’.
But the overall point is the dozens of wounds it should have been obvious not only to the ME but to anyone who was trained whether the wounds were rifle or handgun.