> Not a reason to violate privacy IMO, especially when at the time this was done these people were only suspected of fraud, not convicted.

Well you can't really wait until the conviction to collect evidence in a criminal trial.

There are several stages that law enforcement must go through to get a warrant like this. The police didn't literally phone up Microsoft and ask for the keys to someone's laptop on a hunch. They had to have already confiscated the laptop, which means they had to have collected enough early evidence to prove suspicion and get a judge to sign off and so on.