I think an employee is stealing from us. Do I call the police or start a disciplinary?

The answer Just Ask, HR gives

Concise Charlie — Direct, no fluff — the bottom line first.

Bottom line: don't march anyone anywhere. You don't need criminal-level proof to dismiss — you need a reasonable investigation. Do that first.

The legal standard is the Burchell test: a genuine belief in the misconduct, on reasonable grounds, after a reasonable investigation. That is much lower than "beyond reasonable doubt" — but "fairly sure" without investigating fails it.

• Tighten the evidence quietly. Stock records against rotas, till data, CCTV you already have. Don't install covert surveillance without advice — that has its own legal regime.
• Suspend on full pay once you have enough to justify investigation, framed as neutral precaution. Restrict system/stock access the same day.
• Investigatory interview before any hearing. Put the pattern to them and listen. Innocent explanations exist — shared logins, process errors, another person's shifts overlapping.
• Then a disciplinary hearing with the evidence disclosed in advance, right to be accompanied, and a decision on the balance of probabilities. Theft is gross misconduct; a genuine, reasonably-grounded belief supports dismissal without notice.
• Police is a separate, optional track. You can report or not — the disciplinary doesn't wait for the police, and a criminal acquittal doesn't make a fair dismissal unfair. Most SMEs report only where the loss is significant or insurance requires it.

The employers who lose theft cases at tribunal almost never lose on "did they do it" — they lose on skipped process: no investigation, no hearing, decision announced in anger. Don't be that case.