Defector from Iranian Nuclear Program?

This story has been popping up for a couple of days in various Middle Eastern media and now I see the BBC has picked it up: supposedly an Iranian working for the nuclear program disappeared while on hajj this year in Saudi Arabia. The Iranians are claiming the US had something to do with it; one version I saw earlier said there were two Iranians missing. The BBC report names one. This has popped up in Al-Sharq al-Awsat and in Israeli papers as well.

I often don't comment on these sorts of things because if it's a defection I'm sure he's safely ensconced in a safe house somewhere and we won't get the full story for a good long time; if it's something other than a defection, we're even less likely to get reliable information. But given the interest in the Iranian nuclear program at the moment, it's always worth noting when these kinds of stories pop up.