Question on use of the 'first' conditional in the past (no modal involved)

Which conditional is this?

If John did not come to work yesterday, he was probably ill.

I would hazard a guess that it is a first conditional as there is a fair probability that John being ill was actually the reason for not coming to work, however all the references I have indicate that the first conditional is for the future only.

Thanks for any comments / explanations!

Edit – a context for clarity: I had imagined a conversation between two work colleagues for example:

Bob: I couldn’t get the numbers I needed from John yesterday as he was
out of the office. Bill: Hmm. If John was out of the office, he was
probably ill. I’ll check whether he is back today and if he is not,
I’ll find some numbers for you