Law enforcement uses this technique when necessary. They also have a device to help move a wall-plugged device without powering it off.

I have heard confirmation of this from friends arrested in the UK (by Scotland Yard) and in the USA (by the FBI). I don't believe they actually witnessed it being done,just that they had what was needed. Though my infosec instructor in university was in the RCMP (Canada) and mentioned hqving done it himself so I'm rather confident law enforcement globally has had this in their arsenal for awhile.