Nope, if they have a warrant, those are legal. There is a name for the ones that you see in the movies, where Clint Eastwood or Harrison Ford is a rogue FBI agent and gets a tip and sneaks into someone's home and steals information off their computer.... usually they find the right bad guy in the movies, in real life, who knows? We don't often hear about these.
I'll give a clue: it's a 3 word phrase, the last word being "Operation".