As far as we'll probably ever know, she was not there when the testers arrived. That's how it was with all of the (reasonably straightforward) whereabouts cases of which I'm aware, from Cabreira to Van Dijk. Who knows whether or not she deliberately misinformed the authorities.
Massive risk to take, especially if you're already on a first or second warning, but I guess Longo was comfortable with it. I say that because what speaks volumes, I think, is that Longo has failed to file her excuses, presumably because in addition to a phone and laptop, she is also averse to fax machines and the postal service. That's why I guess this is still an investigation rather than a witch-hunt.