Police are investigating the blackmail of television mogul John de Mol and threats made against his sister Linda, a television presenter and actress, Dutch media reported on Tuesday.

Details of the case are sketchy but a drawing of ‘a man who is definitely concerned with the case’ will be shown on television crime show Opsporing Verzocht on Tuesday evening.

Police have declined to give any more details about the case or what the man on the drawing is said to have done.

However, according to news agency ANP, security at Linda de Mol’s home was stepped up at the end of last year because of threats made against her.

John de Mol is the multi-millionaire owner of production house Talpa and was one of the founders of the Endemol entertainment empire. He was the subject of a previous blackmail attempt in 2005.

Linda has a successful career presenting game shows and acting in popular series such as Gooische Vrouwen.