This website provides an avenue for investigation, and offers a sliver of hope. It’s a tiny sliver of hope to be sure, but it’s better than no hope at all.
It works like this: You upload a picture taken with the missing camera to stolencamerafinder.com, which then uses the camera’s serial number (saved in the photo’s EXIF data) to crawls the internet in search of other photos taken with that same camera. If it finds a match, you may have a lead on where your camera ended up.
From there, you can try to track down and contact the “new owner” via email to request your camera’s return, file a report with the authorities, or devote your life to hunting the thief yourself, John Wick style.
None of these options is likely to result in the return of your Nikon, but it has worked in the past, and maybe it will help you find closure. Maybe just knowing what the hell happened to your camera is the best you can hope for? And the site also provides a database of lost cameras all over the world, so you’ll at least know you’re not alone.