Must be pretty clear that this was the primary reason for the sucide. Mentioned it in their suicide note, had expressed such fears to aquaintances, took steps to ensure their brain was unrecoverably destroyed, etc.

It must be a true counterfactual suicide, where they wouldn't have just done it for some other reason if they didn't know about AI risk.

The reason for the suicide must be fearing a fate worse than death from an AI that chooses to make humans suffer in some way rather than killing us outright.

If this has already happened in the past, I'll count that too.