Mouschi went missing.
Peter’s cat, Mouschi, was a pet that lived with him during a particularly difficult time. Peter, referring to Peter van Pels, was one of the eight people in hiding during the Holocaust, as chronicled in Anne Frank’s famous diary. Mouschi was brought into the Secret Annex where the families were hiding. Cats in such circumstances often roamed freely and sometimes went in and out of their hiding places. Unfortunately, at some point, Mouschi disappeared and was never found. The exact fate of the cat is not recorded, but given the perilous situation and the many dangers of the time, including scarcity of food and the risk of discovery, it’s likely that Mouschi could have wandered off and been unable to return, or may have been taken in by someone else if he was found outside the Annex.