The murder of Boris Nemtsov is beginning to look like a catalyst for some significant upheaval in Russia.
The arrest of Chechen suspects initially looked like a lazy round up of the "usual suspects".
However it quickly became clear that the individuals detained by the FSB were not just ordinary Chechens but significant figures, very close to the Chechen strongman, Ramzan Kadyrov, who has enjoyed special privileges both in his home patch, but also across Russia, including Moscow. Privileges which were, of course, granted by Putin.
The fact that the head of the FSB personally announced the arrests -a very unusual thing for him to do- suggests a major split between two of the critical pillars of Putinism: The FSB and Kadyrov's Chechens.
This is now a major headache for Putin.
At other crisis points -the Kursk disaster springs to mind- he has dropped out of sight and then returned, usually with increasing levels of ruthlessness, and, amid swirling rumours, that seems to be what he is doing now: he has not been seen in public for several days.
However, Andrei Ilarionov, who has a track record of being a very well informed Kremlinologist, suggests that Putin is facing a direct and personal challenge to his authority, and that even a Palace coup is now a real prospect, with the ouster of Dimitri Medvedev as Prime Minister and his replacement by a figure closer to the FSB. This would matter intensely, since the PM is the designated successor if the President steps down or is removed from office.
Clearly the removal of Medvedev has been a possibility for some time now, but Putin knows he must tread exceptionally carefully in his choice of successor, and even more carefully if the FSB and the Chechens are now on a collision course.
So in addition to the international pressure on the Russian leader, it now seems that internal pressure from the regime itself is making itself felt.
Late stage Putinism is at a crossroads this weekend. It may be that Putin is indeed facing real pressure from the hardline Russian nationalist tinged FSB leadership. Yet to concede to their demands could destroy the delicate balance that has been struck, not only with the Chechens, but also the many other nationalities of Russia, such as the Tartars, which risks destroying Russia as we have known it. On the other hand, failing to deal with the murder of Nemtsov could lead to a St Valentine's Day Massacre of the leadership as the different oligarchs panic over their own position. Wild rumours of the arrest of Sechin seem wide of the mark, but there are any number of strange stories in Moscow these days- and not just the tosh put out by Dimitri- the "Mouth of Sauron"- Peshkov.
Clearly Putin is in a very real mess, it is no wonder he has gone to ground. He must resurface to meet the Krygyz President on Monday- and a failure to do so could create a rumour firestorm. By that time he must have worked out a new domestic balance, and a failure to do that could make his life very dangerous indeed.