| Koos Hertogs | |
| Birthname: | Jacobus Dirk Hertogs |
| Birth Date: | 16 December 1949 |
| Birth Place: | The Hague, Netherlands |
| Death Place: | S-Hertogenbosch, Netherlands |
| Victims: | 3 |
| Country: | Netherlands |
| Beginyear: | 1979 |
| Endyear: | 1980 |
| Apprehended: | 3 October 1980 |
| Sentence: | Life imprisonment |
Jacobus Dirk (Koos) Hertogs (The Hague, 16 December 1949 – S-Hertogenbosch, 19 July 2015) was a convicted Dutch serial killer. He was convicted of a total of three murders.
Hertogs was in a homosexual relationship with, Vice President of the court in The Hague.
After the murder on Edith Post, the police received an anonymous call with the information that Edith had bitten her murderer, and a bouncer of nightclub "De Nachtegaal" (The Nightingale) had a severe bite wound on his little finger. The bouncer, who was subsequently arrested, turned out to be Koos Hertogs. Police searched his house and found traces of blood matched to Tialda Visser and Emy den Boer. In the attic, police found an insulated room. It is believed that Hertogs hid and raped his victims here for a period of time, before killing them. Hertogs was sentenced to life imprisonment. Until 1989 Hertogs denied killing the girls. However, after consultation with his lawyer, he confessed so he could be placed on a lighter regime.
For a long time, there were rumours that Hertogs had protection from high-level individuals. In the book Zuidwal, which tells the story of the serial killer, it is claimed that Hertogs was protected by Cornelis Stolk, an important judge and vice president of the court, however, both men denied the claims. In 2009 crime reporter Peter R. de Vries started a sting operation, trying to reveal if Hertogs murdered more people or if the claims made in the book were true. While being filmed with hidden cameras, Hertogs, talking with a 'dear' friend, who turned out to be an infiltrator working for De Vries, made some notable admissions.
In August 2012 writer and psychologist Patrick Oomens published the book De zaak Koos H., in which he questions the claim that Hertogs is a serial killer and concludes that he does not fit the profile. According to Oomens, that would shed light on the case and claims that the case of Hertogs has characteristics of a cover-up with connections to Operation Gladio. With respect to the 'befriended' psychiatrist, the writer claims to have discovered that the ex-wife of Stolk wasn't a psychiatrist at all, but in reality, the first female pilot in the Netherlands who transported the Dutch Royal family in the early 1950s.