In the bombings of the US Embassies in Africa and in the bombing of the WTC in 1993, there was clear and convincing evidence that Osama was guilty.
It was simply that he was on the loose that kept him from being convicted.
Therefore, whether or not he committed these recent acts, he deserves death.
The plan in 1993 was to topple the WTC towers. Only faulty engineering on the bomb makers' parts caused it not to occur. Those bombers should be treated just the same as the terrorists who actually succeeded.
(corrected date -- thanks)