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A nephew of Anis Amri, the Tunisian man believed to be responsible for this week's deadly attack on a Berlin Christmas market, was among three people arrested in Tunisia on Saturday and held on "suspicion of belonging to a terrorist organization and connections with terrorist offenses." The nephew has not been named by authorities.

CNN reports Amri, who was killed by police in Italy, asked his nephew to pledge allegiance to the Islamic State. The two were in communication via an encrypted messaging app, but police have not determined whether Amri conducted his attack alone or with assistance from his nephew or others.