No. With on-demand logging, they can find the owner of the account (assuming he doesn't take further measures), but you can't retroactively prove someone used t

No. With on-demand logging, they can find the owner of the account (assuming he doesn't take further measures), but you can't retroactively prove someone used that account to do something at a specific time. For example, you could not prove that the individual was logged in at internet cafe xy near the time of the crime. Also, an opsec mishap (such as logging in without protection) will not be fatal unless you're already under surveillance.