(CNN) -- Police in Brazil say they have arrested a fourth person in connection with the March 30 rape of an American woman and the beating and robbery of her French boyfriend on a minibus in Rio de Janeiro.
The fourth person arrested -- a 13-year-old boy -- is accused of helping steal the tourists' credit cards, police said Tuesday.
According to Brazilian media, the boy has denied involvement in the rape.
Police said the woman and man boarded the minibus in the Copacabana beach district in Rio de Janeiro early on March 30. Three men subsequently boarded the minibus and forced off all the other passengers, police said.
The woman was raped and her boyfriend was held captive and robbed, authorities said.
Their credit cards were used at several locations inside and outside of Rio de Janeiro over a span of hours, police said.
According to Brazilian newspapers, the man was handcuffed and beaten, while the woman was repeatedly raped. The two were dumped in Itaborai, a city more than 30 miles (about 50 kilometers) away, after six hours, O Globo newspaper said.
Earlier, police arrested three other people in the case: Carlos Armando Costa dos Santos, Jonathan Foudakis de Souza and Wallace Aparecido Souza Silva.
The rape highlights security concerns in the Brazilian city that will host matches in the 2014 World Cup and will put on the Summer Olympics two years later.
As more women came forward saying they were victims of similar attacks, Rio de Janeiro Civil Police Chief Martha Rocha issued a written apology. She also fired two police officers responsible for handling rape cases.
CNN's Shasta Darlington contributed to this report from Sao Paulo, Brazil