Kaplan was thought to be on the run after a German court cleared the way for his extradition to Turkey, but his lawyer told authorities the Islamist cleric remains in Cologne and will turn himself in next week, German newspaper Die Welt reports.
"He never went into hiding, why should he?" Kaplan's attorney said. "He simply wasn't home (when police came to arrest him), and he wasn't under house arrest."
Kaplan, who calls himself the "Caliph of Cologne," is wanted in Turkey for allegedly conspiring to blow up a memorial to the country's founder, Mustafa Kemal Ataturk, with an explosives-laden airplane.
He could appeal his extradition to Germany's supreme court.