Did X1 witness, compelled to murder, Katrien De Cuyper at Castle Kattenhof in 1991? We won't know for sure unless the investigation is reopened with the knowledge of X1's testimony is still credible even though minor details have differed. With all the connections between the people accused by X1 are put into view, it enhances the case rather than discredit it.
"No one will believe you Regina [Louf/X1]. And those who do will be destroyed. I am protected by powerful people. (Antoine “Tony” Van Den Bogaert, as quoted in Regina Louf’s autobiography)