Theory:
The Coffin Arthur M. was making, was for himself.
Why?
He transfered his Sisters ashes into the small "portable" glass vile for the trip to Tampa. This preperation was done prior to Dexter admitting to Arthur about him killing an innocent. The suicide attempt had nothing to do with Dexter or any revelations that came as a result of him and Dexter being "the same". The whole reason for the trip to tampa was to kill himself. Perhaps because after 30 years and using almost all the ashes, he'd come full circle, back to where it all started. This exit was inevitable in Trinity's mind.
The Shooter:
I posted before who I thought the shooter was a while ago, Obviously I was wrong.
#1-Trinity
#2-Jonah Mitchell
#3-Christine (the reporter)
Well, I guess I can scratch my first choice off the list!
...So now I think Jonah (Mitchell's son) shot Lundy and Deb. Simple explanation. Arthur made him do it. Just like Arthur could not kill the deer, (even though it had to be put out of it's misery) he could not kill Lundy either, even though it absolutely had to be done.
....Either that or it was
LEGUERTA!!!!
....I just can't think of any good enough reason why she would do it though.
I think it may be possible that Arthur's Family knows more about Dads activities than we think. But Arthur has a strong hold on all of them and is in complete control of his Family, as depicted when the son was washing the car, the daughter watering the plants and the wife getting his clothes folded and bringing
only him a refreshing drink and not the children.
On a Side Note:
The whole Leguerta/Batista thing is soooooo not interesting. Does anybody (viewers) really care if they are bumping uglies or not?...Cuz I sure don't. The only good that has come of that whole story line, was when Batista broke the "previously weakened" table. That was funny.
Deb, even though She has somewhat of a "Boyish" figure, looked kinda sexy when showing off her gunshot wounds, Masuka was Hilarious!!
Quinn is making it a real pet project to get under Dexter's skin and trying to find out what makes him tick, It's interesting and creates a nice level of tension for the show.
Sorry to add this, every show has it's weaknesses in terms of the writers getting away with B.S. But I thought 2 instances in particular were just plain unbelievable:
When Arthur & Dexter went to Arthur's boyhood home and were having their conversation in the bathroom, I find it hard to buy the fact that it took the oriental couple that long to come upstairs and ask them to leave.
Also, when They were driving back to Miami in the Van, and in line at the police check point, I find it hard to believe that somebody could just pull a u-turn that easily and avoid being checked.
.....Just some thoughts,