Venezuela orders arrest of opposition leaders over disputed region vote
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Venezuela's attorney general ordered arrest of 12 opposition members, including Juan Guaidó and 3 of Maria Corina Machado's campaign staffers
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Accuses them of conspiracy against referendum on disputed Essequibo region held Sunday
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Also linked US citizen Savoi Jadon Wright, arrested in October, to the case
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Machado calls referendum turnout a "monumental defeat" for government
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Family says Wright was wrongfully arrested and being held for ransom after US eased Venezuela sanctions