The Garda Síochána Ombudsman Commission has confirmed it is investigating a complaint by Marie Farrell about gardaí investigating the murder of Sophie Toscan du Plantier.
The Irish Times understands that Jules Thomas, an artist, has also lodged a complaint with the ombudsman over her treatment by gardaí.
There was a similar complaint by her partner, Ian Bailey, over his treatment by gardaí.
Mr Bailey was twice arrested for questioning about the murder of Ms Toscan du Plantier at her holiday home near Schull in west Cork in 1996. He has always protested his innocence and has denied any involvement in the murder.
