Though you can investigate but I suggest starting with some solid proofs.
This is what i did for almost two days (checking post history of one user took two days without any result), but maybe because am not professional in doing this (don't have tools or skills) i just thought that this thread may take the attention of investigators willing to help.
I am also not able to find anything which is used by someone else as well. I think it is better to leave the case atm since it contains inconclusive and not a solid proof.
I would though keep an eye for this user. Thanks for reporting.