So you are telling that this is not a SAP report at all, it is just an Excel spreadsheet and you want know from where (which transactions) he could have get the values for the individual columns?
Did he die or leave in anger? I would not have a problem to contact him even he has left the company. HR department usually has contact information. And many colleagues probably too as the the relationship that was built over the time does usually not cut off when one is changing jobs