A man who hid from the Charlie Hebdo gunmen is suing French media who revealed his whereabouts.
Lilian Lepere stayed under a sink for eight hours after the gunmen began a siege at the printing shop in which he worked in a Paris suburb in January.
The men - Said and Cherif Kouachi - had killed 12 people at the Charlie Hebdo magazine the day before, and were later shot dead at the printing shop.
Mr Lepere says his life was endangered by details revealed on TV and radio.
The initial allegation of a man hiding at the factory in Dammartin en Goele was made on the RMC radio station by the area's French assembly member, Yves Albarello.
The claim was then repeated by the TF1 and France 2 television networks, two of France's largest.
Mr Lepere's whereabouts were also confirmed to France 2 by his sister, although it was never stated exactly where he was hiding.
After Mr Lepere's boss was freed by the gunmen, he continued to hide under the sink until the siege ended.
Mr Lepere then gave a detailed interview about his ordeal to France 2.
He lodged a complaint with prosecutors in Paris last month, and an investigation against the networks was launched last week, French media say.
"The divulging of information in real time, while the Kouachi brothers - armed and dangerous - were able to follow how the operation was going, presented a real risk to Lilian," his lawyer, Antoine Casubolo Ferro, told Le Parisien newspaper.
The networks have not responded to the investigation.
In April, another lawsuit was lodged by survivors of a siege at a Jewish supermarket in Paris, that took place two days after the Charlie Hebdo massacre.
Gunman Amedy Coulibaly killed four people at the Hypercacher Jewish store on 9 January before police shot him.
Six of the survivors filed a lawsuit against television networks, saying live images broadcast from the supermarket scene "lacked the most basic precautions".