/usr/lib/parmetis-int64/libparmetis.a is in libscotchparmetis-dev 5.1.12b.dfsg-2+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/parmetis-int64/libptscotchparmetis.a
/usr/lib/parmetis-int64/libptscotchparmetis.a