According to La Tribune de Genève, the girl's father reported her missing on October 29th at around 1.25pm in the centre of Geneva.
Police immediately launched a search in the area, and in Servette, where the girl's mother lives, said the paper.
However it is now known that the seven-year-old boarded a train for Geneva airport and entered the French sector, passing through the customs point where officials are not always present.
More surprisingly, she then managed to pass through the security gates without showing a boarding pass.
Speaking to the paper, airport spokesman Bertrand Stämpfli said surveillance videos show that the girl was not asked for her boarding pass.
“She apparently managed to make out she was with the adults in front or behind her,” he said.
She then attempted to board a plane and, despite being turned back on trying to follow crew members, eventually managed to board by avoiding usual channels and sneaking in "through a passage only accessible to a child of that size,” said Stämpfli.
Though she managed to get on the plane she was then spotted and stopped by a staff member and finally taken in hand by police.
“It's not about pointing the finger at one person or another in this story,” Stämpfli told the paper. “We must take collective responsibility.”
Steps have already been taken to ensure that such an incident can't happen again, such as installing plexiglass to ensure a child can't slip under barriers.
“We must acknowledge that the current system is efficient for adults and accompanied children but that it must take better account of the weaknesses that could let a child slip through, as this unprecedented and regrettable incident has shown,” Stämpfli said.