That's a very unusual and narrow exception involving "foregone conclusion doctrine", an important fact missed by Ars Technica but elaborated on by AP: https://apnews.com/general-news-49da3a1e71f74e1c98012611aedc...

> Authorities, citing a “foregone conclusion exception” to the Fifth Amendment, argued that Rawls could not invoke his right to self-incrimination because police already had evidence of a crime. The 3rd Circuit panel agreed, upholding a lower court decision.

I do not follow the logic here, what does that even mean? It seems very dubious. And what happens if one legitimately forgets? They just get to keep you there forever?