[zaarn]

For dead authors, the inheritance regulates who gets to control the copyright. Usually inheritance works out, the state puts a lot of money into finding lost relatives if everything else fails.

The publisher to my knowledge cannot claim copyright over composition, layout, typesetting or the PDF unless they can show they had significant copyrightable work in each step. (Copyright in Germany first requires you to do some significant intellectual work, where significant changes based on what you do but science usually has a higher barrier)

If the PDF contains a trademark of theirs then that's a problem.

Generally a pre-print PDF should be available in almost all cases and could be published without Elsevier's input. If not that, Universities do archive the Tex files (or similar inputs) if possible so they could take those.