She disappeared after meeting with an ex-boyfriend, Filippo Turetta, 21, at a mall; investigators put out a warrant for his arrest on suspicion of kidnapping and murder.
He was picked up on Sunday by the police in Germany, who stopped him on a highway.
Investigators have not spoken publicly about a motive in the case.
Mr. Turetta, who has so far not been formally charged, is awaiting extradition to Italy, which the German authorities say he has not opposed, according to his lawyer, Emanuele Compagno.
Mr. Compagno said he had not spoken directly to his client.
Persons:
Giulia Cecchettin, Cecchettin, Filippo Turetta, Turetta, Emanuele Compagno, Compagno
Organizations:
Investigators
Locations:
Friuli, Giulia, Germany, Italy