Loading ...and implies that these people were killed because of them. You can’t have a secret patent. It would defeat the object of the patent system. Patents fulfil several functions, one of which is granting ownership of an idea for commercial purposes, another is letting everyone know that they can stop trying to achieve something because it has already been done – and this is how it works. If the patent is for cold fusion, for example, it’ll tell you how to make electricity in a particular way. If you find a different way to get cold fusion to work, you can get your own patent.
Best still, if it’s been patented you can find the patent and build your own cold fusion machine! You can use a patent for personal use.