Jacques Moretti, the owner of the Constellation bar in the Swiss resort of Crans-Montana where 40 people, including six Italian teens, were killed in a fire during a New Year's Eve party, was arrested on Friday.
Corsican-born Moretti was taken out of the courthouse in Sion in a police van after questioning.
His French-born wife, Jessica Moretti, walked out of the building accompanied by her lawyers.
The decision not to arrest the owners of the bar immediately after the disaster was widely criticised.
Jacques Moretti has a criminal record in France, including a jail term handed down in October 2008 over prostitution-related offences, according to French media.
