The Public Prosecutor “Hecker” and the “Neue Rheinische Zeitung”

Summons, appeared and was heard for the record. The compositors were, as far as we know, summoned as witnesses, the proofreader was summoned as a witness, the printing house owner was summoned as a witness. But finally, the editor was summoned as a witness. We do not understand the last summons.5
Is the alleged author to testify against his accomplice witness?
To be complete in our historical narrative: a house search was conducted in the office of the “N. Rh. Z.”