Docusign expert/consultant needed for signature authentication dispute

I have a client who disputes a docusign Certificate of Completion.  He believes the person who created the envelope also signed it as the recipient without his permission.  I have the Certificate and some of the metadata from Docusign's response to my subpoena, but I need an expert to help me understand what I am looking at, draft additional subpoena's and deposition questions and perhaps testify at trial depending on what we discover.