http://www.independent.co.uk/news/wo...-10131891.html
French Transport Minister Ségolène Royal confirmed a French military Mirage jet fighter had investigated soon after the aircraft stopped respondingat 10.30am. The warplane was seen by eyewitnesses, following the airliner as it skimmed the Alpine ridges before it crashed. The pilot of the Mirage could, therefore, also possess crucial information on the Germanwings aircraft’s behaviour.
Note the last line is commentry by the writer, it is not confirmation (beyond the eyewitness) that a Mirage caught up to and tracked the flight.