Did Eric shoot Dylan?

There are popular theories stating that Eric actually killed Dylan with the TEC-9 first, put the TEC-9 in Dylan's right hand (in an attempt to make it so it looked like he killed himself), before putting the shotgun into his mouth. I'm not saying I believe this theory, but I find it quite interesting, mainly because there was an entry wound (from the TEC-9) in Dylan's LEFT temple, but the TEC-9 was lying in his RIGHT hand. What do you guys think?

The Tec 9 must've fallen between Dylan's legs and that's just how he landed on it. It's also important to remember that those photos of them were taken after the swat searched their bodies.