A Brazilian judge on Monday ordered the arrest of a man suspected of being involved in an alleged plot to place explosives at a concert by singer Lady Gaga in Rio de Janeiro. Judge Fabiana Pagel of the Rio Grande do Sul state court did not name the suspect in her ruling, but said he is a man investigated by Rio de Janeiro police as the alleged mastermind of the plot. Police in Rio Grande do Sul state, which borders Argentina and Uruguay, said Sunday they had released a man under investigation for the alleged plot after he paid his bail.