Do the routine test first

Human error is a part of life that can rarely be eliminated entirely. Disciplinary actions are usually not appropriate when slips, lapses or mistakes have been made because they can lead to a feeling of injustice, but many things can be done to prevent their (re-)occurrence. To determine the right course of action, once you have established the behavior of the person in question is a slip or lapse, one has to ask the question: "does this happen a lot"? Humans are not machines, and they will make human errors. Ordinary people may repetitively complete a procedure ten times in a row without an error. A specifically trained human operator could perhaps do this a hundred times in a row without errors.

You now need to establish three things:

1. This never happened before

2. It happened before and the same person

3. This could happen to anybody.

Select one of the above for the followup.