I am a PhD student. A few years ago, I won the best paper award at a conference. However, they didn't post the list of winners on the conference website. But when I google the name of the conference, the very first search results include someone who already graduated and claims on his personal webpage and LinkedIn profile that he won that award. The only proofs that I have are the award itself and a congratulation email from the committee.
Currently he works at a company so I don't know how to handle this case especially after his graduation he may no longer care about consequences.
What can I do in this situation?