Senators Barbara Boxer and Jay Rockefeller, both Democrats, were particularly interested in information on Les Hinton, the former Dow Jones chief executive and publisher of the Wall Street Journal.

Hinton stepped down from his position in response to the scandal on July 15, ending a 52-year career with News Corp. He had previously been chairman of News International whose now defunct weekly tabloid News of the World is at the center of the phone hacking uproar.

The Dow Jones special committee was created in 2007 to help ease concerns of the Bancroft family, who owned Dow Jones, publisher of the Wall Street Journal, before it was bought by Rupert Murdoch’s News Corp.

News Corp. has so far been able to keep the impact of the phone hacking scandal mainly to the UK, and away from the United States, where News Corp. is headquartered.

In the letter, the senators asked whether the Dow Jones Special Committee plans to conduct a broader investigation that includes an examination of whether former senior Journal or Dow Jones executives had knowledge or a role in alleged criminal activity at News Corp. publications.

Several members of the committee were not immediately available when Reuters attempted to contact them.

The five member watchdog group was set up to police the editorial independence and integrity of the Wall Street Journal and Dow Jones under News Corp’s ownership.

The special committee released a statement after Hinton resigned last Friday, stating that it was monitoring the situation

Hinton served at News International, the British newspaper arm of News Corp, during the most serious phone hacking allegations at the News of the World.

The panel has said it has no reason to believe that Hinton’s departure was related to activities by the Wall Street Journal or Dow Jones “or that any of the London offenses or anything like them have taken place at Dow Jones.”

Reuters is a competitor of Dow Jones Newswires, the financial news agency that News Corp. acquired along with the Wall Street Journal in 2007.