Re: Statute of limitations
Check your Vienna Conventions. They are quite clear that embassies are not sovereign territory.
However, the hosting state makes an agreement not to enter diplomatic premises without the prior consent of the ambassador, or their government.
There are then rules that say that no embassy is allowed to be used for activities incompatible with that diplomatic status, such as spying, criminiality and the like.
However, there's no enforcement mechanism for either. Or even a proper means of arbitration. Which is a problem with international law generally. So how do resolve disputes? Generally negotiation. So we let the Libyans off with murdering a British police officer - because to do otherwise was too damaging to vital tools of international diplomacy. We did however kick their entire embassy out of the country afterwards. Sending the police in might have led to some poor UK ambassador not being able to face down an attempt to force entry to a British embassy in the future. For the same reason, nothing was done about Assange, even though we don't recognise a right of sanctuary in embassies - something that is common in South America, but not recognised by the international conventions. In South America it means the government can get out alive during military coups, if they can reach an embassy.
However, it is true that Ferroro Rocher are compulsory at all ambassadorial receptions...