/usr/lib/x86_64-linux-gnu/libsuperlu.so is in libsuperlu-dev 4.3+dfsg-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libsuperlu.so.4.0.0
/usr/lib/x86_64-linux-gnu/libsuperlu.so.4.0.0