Gathering before explaining
The instinct is to reassure immediately, and it is a mistake. A supervisor who says the crew definitely attended and then discovers they did not has created a much larger problem than a missed shift. The correct first response is that it will be checked and an answer will be given the same day, which is honest, achievable and does not commit anybody to a position they may have to reverse.
The records available are usually sufficient. Sign-in and sign-out times, the exception log, building access records where the site has them, and the cleaner's account. Where a building has electronic access control, the answer is frequently definitive within a few minutes. Where it does not, the combination of the crew's records and the physical state of the building usually settles it. The physical state of the building usually settles what the records leave ambiguous.
