If it was the same gun that was used then maybe Emily got it off Tug. I know what your thinking, that she couldnt have taken his gun. Easy enough if she hugged him and took it outta the back of his jeans. not the most secure place to keep a gun.
Why has it been assumed that it was Tug that was meeting her at the tunnel though. We have nothing to suggest that it was him. All we have is a piece of paper with one of their (Pin and Tugs groups) call signs on. Anyone in the know could have passed it on.
I dont see how it works being Tugs gun that killed her though. Really confuses me. As Tresh248 pointed out
'There is no possible way that Tug shot Em and there is absolutely NO way that he shot her in the face. The reasoning behind this is two fold. The slightly weaker reason is the nature of our protagonist Brendan. There is no way our super sleuth would miss a gunshot wound especially if he physically moves the body to a hiding spot. The second reason why this couldn't happen is because of how gun shots work. Guns and bullets especially of the size that would come from Tug's gun leave exit wounds. The entrance wounds are actually smaller and then leave large holes where they exit as the bullet encounters mass which slows it down and causes it to rip a large chunk of flesh as it exits the body. '
And we have seen what Tugs gun did to Dodes head. Nice big exit wound and a loverly spray of blood. So can we assume from this that Emily was not killed by the gun, or maybe not at the tunnel. There would be evidence, no matter how much of stream shes partcially lieing in. But what if she wasnt killed at the tunnel? What if someone in the know about the meet killed her and took her there, because if it was the person who organised the meet why would you kill her elsewhere and take the body to somewhere a handful of people knew she would be?
And like jane said
'Not that we can trust that anything Laura says is the truth...'
How would Laura know if it was the same gun? The fight took place at 4:15 am, and when she met Brendan it was still pretty early on in the day (as Brendan had posted the not to the AVP and Laura had not yet been picked up). How would she know? I dont know if America police work A LOT quicker than ours (doubt it as guns are still a big thing in blighty) but took only 4 hours to find Dodes corpse, remove any bullets there may be (remembering that without a bullet they could only know it was the same calibre used, and to find the bullet from Dode they would have to dig it out of the tunnel wall), send them to ballistics, get the results back and give a press statement. I dont think so. So this is either a lie or she knew it was the same gun anyway.
If it was the same gun Brendan would have known she had been shot, and surely have a good idea of the size gun responcible. This is an astute, street smart kid we're talkin about. Yet there was no mension made to a gun at any point during the film, nor, if I remember correctly, was there any more of a confesion from Tug than killing Dode. No thats a bit much for me. She's lieing or knew it was the gun and Tug wouldnt have told her if he had killed Emily would he? So, the only way that she could have known is if it was her that had done it (or she had got someone else to)
Motive - as explained at the end, to save herself.
Opotunity - She could have taken it if it was left unattemded at the Pins house and returned it after the murder. And she too, would know the signs. New suspect (though I still like suicide) Laura.