Israel "Vague" on Assassination

I'm in absolutely no position to comment definitively one way or another on this issue, but it does strike me that if Israel hadn't been behind Mugniyah's death, they'd be much more forceful in their denials than they have been:

Senior Israeli officials have not commented publicly about the assassination, widely hailed here as a brilliant intelligence coup. Instead, there was an ambiguously worded statement issued by the office of Prime Minister Ehud Olmert on Wednesday distancing Israel from the act, and what the Israeli news media described as “mysterious smiles.”
Some here saw Mr. Olmert’s vaguely worded statement — “Israel rejects the attempt by terrorist elements to ascribe to it any involvement whatsoever in this incident” — more as a nonadmission of responsibility than an outright denial.

I don't know about you, but if lots of people thought that I'd killed someone, and I hadn't, I don't think I'd be smiling much, mysteriously or otherwise.