/usr/lib/x86_64-linux-gnu/metis-int64/libmetis.so is in libscotchmetis-dev 6.0.4.dfsg1-8.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/metis-int64/../scotch-int64/libscotchmetis.so