If you are looking for a free, interesting, home-based hobby, and enjoy research, consider becoming an internet sleuth. People have been using the power of the internet along with crowd-sourcing to solve crimes for more than a decade (examples here, here, and here).
Web sleuths use a number of crime-solving websites to search for information matches and clues then pass them along to law enforcement. Websites to check out include the Doe Network, NamUs, Web Sleuths, The Charley Project, and Unsolved Mysteries. There are also several Facebook pages and groups that focus on specific cases. Of course there are subreddits for all sorts of crimes (see sidebar here).
This is an interesting way to spend your downtime and could help resolve cold cases that would not otherwise be solved.