The resignation of Rebekah Brooks may have mitigated some of the ongoing fallout from the British phone-hacking scandal that has engulfed his media empire, but Rupert Murdoch is facing a mounting legal challenge in the U.S. on various fronts.

Not only is the FBI investigating his News Corp. over allegations that it may have hacked phones of the victims of the Sept. 11 terrorist attacks, but his own corporate board members and shareholders may sue him and his son.

According to a report in the British newspaper Daily Telegraph, top News Corp. shareholders could launch a “shareholder derivatives” lawsuit against the Murdochs, father and son, for failing their “fiduciary duties.

In fact, some shareholders, including Amalgamated Bank and Central Laborers’ Pension Funds, have already filed such a suit over the way the Murdochs run the company – but more are likely on the way.

However, that may only be the tip of the iceberg of the legal woes the Murdochs could face.

In relation to illegal phone hacking, they could face a raft of charges coming under the auspices of anti-corruption, privacy and obstruction of justice laws, including the Racketeer Influenced and Corruption Organizations Act (RICO), which has been successfully used against mobsters.

Conviction on such charges can be as high as 25 years.

Ann Fitz, a specialist in corporate crime law, told The Daily Telegraph: “RICO could land the Murdochs in jail if they are found to have made fraudulent representations to shareholders and the public. They could also be charged, separately or together, if they conspired to keep [criminal practices] within the company a secret. They could also be charged under obstruction of justice.”