Christian Brueckner reportedly flew from Portugal to Germany to have the almost $15,000 surgery.
Investigators may have found fibres of the girl's pyjamas in a man's car.
"But they had not even one proof that I was involved with the McCann case. And they still don't have it."
They welcomed the news Christian Brückner has been named as a formal suspect.
Here's what we know.
McCann went missing in 2007 from a resort in the seaside town of Praia da Luz in Portugal.
Christian Brueckner was also "no more than five minutes away" from the resort when McCann vanished.
McCann went missing in Portugal in 2007.
The prosecutor is yet to speak to the suspect.