No Ubuntu packages will install anything to /usr/local, it must be something you installed manually or a .deb you installed from a 3rd party repository. If it's the latter you can find the package with: dpkg -S usr/local/lib/libQtCore.so.4
No Ubuntu packages will install anything to /usr/local, it must be something you installed manually or a .deb you installed from a 3rd party repository. lib/libQtCore. so.4
If it's the latter you can find the package with: dpkg -S usr/local/