The proportions were wrong.

The specific configurations of the ridges and curves were different.

This was not proof of impersonation by itself — photographs can be of poor quality, comparisons can be misleading, and ear comparison is not infallible.

But it was enough to motivate Parker to pursue the fingerprint path.

He sent Bourdin’s fingerprints to Interpol.

Interpol compared them against their database of European criminal records and returned a match to Frédéric Bourdin, a French national with a history of identity fraud.

The match was unambiguous.