"The last gang robbery (despite patrols checking the supermarket every twenty minutes) led to rumors of them having some kind of inside knowledge and possibly complicity by individual gendarmes in the attacks. Nearby Gendarmerie vehicles (which had a semiautomatic FN Uzi in a compartment) did not engage or pursue the gang. The Belgian "stay-behind" network SDRA8 (Gladio) — operating as a secret branch of the Belgian military service — was suggested by some to have links to the gang. Some units of the stay-behind network were made up of members of the Belgian Gendarmerie. One theory was that the communist threat in Western Europe was taken as justifying Operation Gladio being activated. However, the Belgian parliamentary inquiry into Gladio found no substantive evidence that Gladio was involved in any terrorist acts or that criminal groups had infiltrated the stay-behind network."
"The role of the CIA in Gladio ... are the subject of debate. The European Parliament resolution on Gladio concluded that military secret services in certain member states were involved in serious terrorism and crime, whether or not their superiors were aware."
But it was a secret, and researched only later.