Tuesday's arrest is the latest development in an ongoing police scandal in which nine police officers had previously been arrested for abuse of power.
During the day, police and investigators have raided around 30 locations, including two police stations in Lisbon.
According to a statement, 24 police officers are being investigated for several cases of torture, rape, abuse of power and aggravated assault. Portuguese media report that most of the victims are undocumented migrants, homeless people or drug addicts.
Police Chief Luis Carrilho says the public can still trust the country's police.
"We have zero tolerance for police abuse," he says.
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