how incredibly sad for the family. There is no excuse if indeed they only used liquid nails or silicone.
*steps on soapbox*
This is why you see so many of us b!tch on here about knowing what you are doing when it comes to installing a sign. I saw a thread a while back about a sign on top of a building that was not mounted safely from the previous sign person and how they - the new sign person - needed to convince the client that the whole structure needed to be redone rather than just replacing a face. Showing them something like this may be the convincing they need.
No one is going to die from a poorly mounted 4mm coro sign. But when you start talking structure and weight load you damn well better have some engineering knowledge of what you are about to install because it IS a real life and death issue if something goes bad. Making the sign is easy, but making sure it is mounted correctly requires not only some common sense, but some degree of engineering and/or construction knowledge.
*steps back off soapbox*