I am using a piece of free source code in one of my projects. The source code was written in the 1990s and is available from a website that says the code may be modified and distributed freely. The source files contain no License indication but they have a "Copyright All Rights Reserved" comment. This morning I started to realize that I may have a License problem because my project is published under the GNU General Public License so I tried to contact the owner of the source code. Unfortunately the owner passed away and thus his company ceased work.
What happens to the source code, is its Copyright sill valid, does it have an owner???