A while back, I invested some funds with a trader and I lost contact with him (long story). I know this is a long shot but I still have the Bitcoin address where I sent the funds originally.
I wouldn't call this an investment, it's more about gambling because you give someone money in the hope that they will trade successfully. At the same time, he is obviously an unknown person to you (otherwise you would know how to contact him).
As suggested earlier, check if his address has been used recently, if not, chances are small that you will find another connection with him.
Have you checked the search engine results for that address? Maybe on another forum, social media or similar...