The new information has been disclosed in a German court.
Madeleine has been missing since she was three years old.
"The bottom line is a little girl went missing in 2007. We do not know what happened to her."
German police believe he may have information about the disappearance 17 years ago.
McCann disappeared while on holiday in 2007.
The main witness in the case could be prosecuted for "unsworn false statements".
It comes 15 years after Madeleine's parents were put under suspicion for their daughter's disappearance.
The large operation saw sniffer dogs, radars and search teams used.
"You can use it to pick any lock, including security locks."
