Board Thread:General Discussion/@comment-12265996-20141202030018/@comment-24942672-20141213132322

http://media.tumblr.com/0491b2ac0008c5bd36d0c4167ee6745a/tumblr_inline_ndeba5fwEh1s1fbpg.png

this is a link i found on a tumblr page called "Gravity Falls Conspiracies" I think it shows that the supects are:

Stanly Pines

Future Mabel

Future Lebam(The supposed doppelganger of mabel)

Though this could be a fake picture i dont really know.