There's one big piece of evidence, assuming that the Portuguese language news reports are accurate. According to this article, Bernadino gave the accomplices $9,000. In a country with an average salary of $250/month that's a lot of money. (Assuming it really was in dollars and not a mistranslation of some other currency.)Is there evidence? Bank, cell phone, witnesses outside of the family? Did Jackie contact Bernadino while they were in the States for four months this summer? What about the money they raised while in the US. Is any missing, didn't travel back to Lubango? Did anyone notice anything peculiar when they were home?
If they can show the cash originated from Jackie it would be a pretty strong evidence of a link between the two.