I can understand the OP going through this carefully as if person is whom he says he is and finds you checking him then a huge element of trust will disappear.......foreever.
OP is being taken at face value the reason why he/she is checking up on this individual.
Its quite possible individual doesn't want to remember his history for whatever reason and I believe there can be many reasons for this.
Person is on the project for a reason and clearly brings some skills onto it but if you feel that it is an issue then request all individuals on the project provide evidence of verifiable career history.