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The suspect had been arrested on Saturday near Leipzig in Germany, the court said, without naming him.
He will be held in custody until he is handed over to Italian authorities, added the court in Naumburg.
The suspect’s lawyer, Emanuele Compagno, had identified him as Filippo Turetta, who went missing more than a week ago along with his fellow student and former girlfriend Giulia Cecchettin.
Her body was later found in a gully near Lake Barcis, about 120km north of Venice, her head and neck punctured with stab wounds.
The case sparked a huge manhunt and made front-page news in Italy over the past week, when the victim had been due to receive her degree in biomedical engineering from the University of Padua.
It was the latest femicide case recorded this year in Italy, where dozens of women have been killed at the hands of their husbands or partners.
In the year to Nov 12, there have been 102 murder cases with female victims in Italy, 82 of whom were killed by family members or current or former partners, according to the interior ministry.
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