Thank you for posting a link. People should shut up about Putin and go look at this. There’s also a photo of the suspect (an older man dressed all in black, with a black cap on and a Muslim-trimmed heard (although he seems to have a moustache). The guy is very weird looking and I’m sure they know who he is.
The only relevant thing to say about Putin, btw, is to note that he is visiting St Petersburg today, and this was clearly meant as a message for the Russian government. St Petersburg would definitely be a softer target than Moscow, where vigilance is extreme.