Kotze was the guilty party.

It was due entirely to this pressure that the kaiser, incensed beyond
measure at the persistency and the malignity of these letters, took
the extraordinary step of having Baron von Kotze arrested by the chief
of his military household, General von Hahnke merely on the strength
of his imperial order, dispensing with any legal warrant. That Count
Hahnke should have been selected for this duty, and that a military
prison, rather than the ordinary house of detention, should have been
chosen for the incarceration of Baron Kotze, must be ascribed to
the fact that the latter was at the time a captain of cavalry on the
reserve lists, and that in a military prison the authority of the
emperor, as head of the army, is supreme and absolute, which cannot be
said of the ordinary civil prisons, the officers of which are subject
above everything else to the tribunals and to the laws of the land.

Of course, from the very moment when the baron was arrested, the
entire scandal, that is to say the existence of a conspiracy for the
writing and distribution of anonymous letters, became public, and
served to furnish material for articles both in the German and the
foreign press on the alleged moral rottenness of the Court of Berlin.
At first there is no doubt that society, and even the ordinary public,
accepted the guilt of Baron Kotze as assured, and were further led
to believe the story about the baroness having been the instigator of
many of the letters, by her at once withdrawing to her country-seat at
Friedrichsfeld, and refusing to receive anyone.

Doubts as to the baron's guilt, however, commenced to arise when it
was found that in spite of his incarceration, the anonymous letters
continued to be sent as before, without any interruption, while all