— He can try but it won't work. In fact, nothing he tries will reveal those names. Sorry, Sherlock. Enjoy being frustrated.
— Yes, there are definite signs that they've been used in a lab setting, for those who know to look for them.
— He would easily notice that there's no sign that these people planned on leaving. No bags packed, nothing tidied away like you might do before a trip, and no signs of a struggle or quick departure. Everything seems completely normal — except that they're not here anymore. Beyond that, nothing of great interest.