Rupert Murdoch and his son James won’t testify next week before a British parliamentary panel looking into the hacking scandal enveloping their media empire, News Corp. Rebekah Brooks, the chief executive of the company’s British branch, has agreed to come forward. Since both Rupert and James Murdoch are American citizens, it is not clear how they can be forced to respond to their parliamentary summons to face questions about the scandal. But the elder Murdoch did say that he is prepared to appear before a separate inquiry led by a judge, and James Murdoch said he can appear in August. Meanwhile, another former editor at News of the World, the tabloid at the heart of the controversy, was arrested on Thursday by Scotland Yard. Neil Wallis is the fourth person arrested in connection with the phone hacking scandal, which allegedly affected victims of terrorist bombings, murders, and the families of dead soldiers. On Wednesday, Murdoch’s News Corp. withdrew its takeover bid for British satellite television operative BSkyB.