Maybe Trevor lansing killed all the people (Leticia, Emily, tried to Kill Carly...) all having to do with his hatred of Sonny?
I don't buy Coop or Logan or Johnny....Too obvious. and it can't be Jerry.
I say if they ever want to bring Emily back, they have to say that she was stangled but did not die, Helena found her barely breathing and gave her that drug that slows down your entire system so that it looks like you're dead...She could take Em to an island and hold her captive a la Laura...
Just throwing stuff out there.
Also, all they had to do to make the Halloween one day Thanksgiving the next was to let everyone change their clothes, have some people healed and gone home to recoup, and have a few say "Wow, 3 weeks and still the investigation is not going anywhere...
How hard would that have been???
Any other theories?