Dear Madam,
You should have, as an HR professional, suggested your approach to this and asked for views from the learned members.
You better find ways to facilitate and enable him , to bring up his performance to expected level by giving him reasonable opportunity.
Every individual has tremendous unutilized potential to cross barriers in performance and it is HR's responsibility to help him bring out to bear it on the job rather than getting into fault finding mode.
Regards,
Vinayak Nagarkar
HR- Consultant