The network had provided the Syrians with birth certificates, identity cards, voters' cards and passports, according to the government news agency Brasil yesterday.
The group was headed by a 71-year-old Syrian with a permanent visa in Brazil, Ali Kamel Issmael.
With the complicity of two civil-registry officials in Rio De Janeiro, the network ripped out pages from birth registries of the 1960s and 1970s and replaced them with new identities, the news agency said.
A majority of the 72 "Syrian-Brazilians" were registered between 2012 and 2014. They include Issmael's wife, Basema Alasmar, who was arrested in the police crackdown.
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As a legal resident of Brazil, Issmael has been released to appear on his own recognizance for a court hearing.
The Rio police believe that many of the Syrians have left Brazil because only 39 possessed the "Natural Persons Register" card known as the CPF, without which transactions as simple as purchasing a cell phone are difficult in Brazil.
The documents scandal has given Brazilians yet a new source of concern as the country prepares to host the Summer Olympic Games next year.
Police commissioner Aloysio Falcao, who is leading the investigation, said the police were asking for the fake passports to be canceled, adding that national security was "at stake.