Yes it can, I know that for a fact.
It doesn't normally do it because it would blow the agents covers and so they rely on "Policia Federal" to carry out arrests.
> they do not have police powers and thus cannot arrest people
Let's face it, that's not exactly what their website says.
A translation would be more like ... policing is beyond their "job scope" and detaining, arresting and interrogating are activities incompatible with the Intelligence work they do - for obvious reasons.
So, saying that they don't detain nor arrest people is fair point.
Although they could detain and so could any other Brazilian citizen detain any person caught red handed (Latin In flagrante delicto) as stated in the Brazilian constitution.
Actually, that's pretty accurately what their website says:
"Can ABIN arrest people? No. ABIN doesn't have police powers/attributions."
Original in Portuguese: A ABIN pode prender pessoas?
Não. A ABIN não tem atribuições de polícia. Deter, prender, custodiar ou interrogar são
atos incompatíveis com a atividade de Inteligência.
Saying any Brazilian citizen can detain someone caught in a criminal act is not what we're talking about here.
