Later in his career, de Vries became one of the most visible figures in the journalistic investigation of cold cases in the Netherlands, such as the death of Nicky Verstappen, in which he supported the victim's family in court.
In 2021, De Vries supported the crown witness Nabil Bakkali in the Marengo process. Less than two years earlier, Bakkali's lawyer, Derk Wiersum, had been murdered outside his home in Amsterdam.[8]
Suspects
The Dutch police arrested three suspects the same day of the shooting.[9] Two suspects were in a car that was stopped on the A4 motorway near Leidschendam.[10] The third person was released the next day, and is no longer a suspect.[11] A 35-year-old Polish man, Kamil E., is the suspected getaway car driver, while a 21-year-old Dutchman, Delano G., is the suspected shooter.[12] Dutch media has reported that the suspected killer is the nephew or cousin of one of the henchmen of Ridouan Taghi, known as the Netherlands' most-wanted criminal.[13][14] De Vries was involved in the prosecution of Taghi.[12]