You’re probably thinking of our army boys stocking up on body bags and lime for their Day X, with kill lists in their back pockets. But yeah, the intelligence service is also suspected to be more or less willfully blind to any fash (with the dude in OP having a big - but not the only - part in that)
On a sidenote: If you wanna get a primer on german cops/intelligence and how they treat Nazis, look up the NSU case.
I’m just gonna quote myself here:
If you really want to rip your hair out you could look up how the cops botched every part of the investigation of this group(NSU) killing Germans with a Turkish background for almost a decade. How the cops at every turn tried to somehow pin it on the families of the actual victims, for example they always thought that the families must be involved in some drug crime or clan activity which led to the murders, never at one point did they even consider racial motivations of the murderers. This only came out when two of the Nazis fucked up and got into a shoot-out with the cops and at the end killed themselves. Not because of the awesome German law enforcement.
All of this series of missteps by the investigators is accompanied by not completely understood activities of our internal intelligence service(former leader Maaßen is an actual right wing conspiracy nut - look up his twitter for a dose of brainworms), the files of that activity are now classified as top-secret and are behind locks for the next 120 years. It is all completely absurd and such a tragedy what has been done especially to those poor families whose lives have literally been destroyed not only by the murders themselves but by the horrible incompetence and outright malfeasence of the state. It is unbelievable.