Kidnappers who abducted the sister of AC Milan striker Ricardo Oliveira had not made contact by Thursday afternoon and police were investigating the possible involvement of one of her sons.
Maria de Lourdes Silva de Oliveira, 35, was abducted by two hooded gunmen who broke into her home in Sao Paulo on Wednesday morning. The kidnappers overpowered her husband and other children before taking her.
Police said one of her sons _ a 14-year-old with a police record _ was considered a suspect.
He allegedly had threatened to kidnap her on other occasions and could have helped the abductors, police investigator Italo Miranda Junior told local media.
Authorities said he might have tipped the kidnappers on how to get into the house, which had the security system turned off when Oliveira's sister was abducted.
Oliveira received the news Wednesday while in Sevilla, Spain, where he was handling personal matters. He hadn't decided whether he would travel back to Brazil or would help the investigation from Italy.
Oliveira constantly was summoned for Brazil's national team until suffering a serious knee injury and undergoing surgery last November. The striker recovered and played for Spain's Real Betis and Brazil's Sao Paulo before joining Milan this year.
The kidnapping was the eighth involving relatives of soccer players in Brazil since November 2004.
It began with the mother of Real Madrid striker Robinho, who reportedly paid a ransom of about US$80,000 (euro63,000) for her to be freed unharmed five weeks later.
This year, the sister of Palmeiras defender Michael and the mother of Santos defender Kleber were kidnapped and released unharmed. Sevilla striker Luis Fabiano, former Sporting Lisbon defender Rogerio, Le Mans striker Grafite, and Corinthians defender Marinho also had their mothers kidnapped and released.