The Huffington Post is reporting that Media Matters has requested Fox News executives and former CEO Roger Ailes “retain any information in their possession or control” that could be relevant  to the network allegedly obtaining the phone records of one of its journalists through “legally questionable means” in order to identify his anonymous sources at the network.

New York magazine’s Gabriel Sherman reported on September 2, that Fox News had “obtained the phone records of journalists, by legally questionable means,” including the home and cell phone records of Media Matters’ senior reporter Joe Strupp, in an effort to find Strupp’s anonymous sources at the network.

Media Matters president Bradley Beychok responded to the egregious allegations and said that the organization is “considering all legal options” available and that “anyone involved in the illegal hacking should be prosecuted to the fullest extent of the law.”

According to the Huffington Post, Media Matters has sent letters to Fox News’ attorneys taking legal steps to ensure that any relevant information about Gabriel Sherman’s allegations is retained:

Media Matters attorney Marc Elias sent letters Friday to attorneys representing Ailes and executives at Fox News and parent company 21st Century Fox, including executive chairman Rupert Murdoch and sons Lachlan and James Murdoch, who serve as executive chairman and chief executive, respectively.

In the letters, Elias requested Ailes and executives at the media companies retain any information in their possession or control that would be relevant to allegations of surveilling Media Matters employees.

Strupp reported in 2010 on Fox News management slanting Washington coverage to the right and cited anonymous sources at the network. Sherman wrote that Fox News wanted to find out who was speaking to Strupp. “This was the culture,” one Fox News executive told Sherman. “Getting phone records doesn’t make anybody blink.”

In addition to Strupp, Elias also revealed in the letters that it “appears that Fox News Channel previously obtained telephone records of Media Matters founder David Brock in 1997.” Brock, a former Republican operative turned liberal Clinton booster, wrote a critical profile of Ailes that year for New York magazine. Brock started Media Matters in 2004 to combat what the group deemed conservative misinformation, with Fox News being one of its primary targets.

“Media Matters takes these reports very seriously and is prepared to take all measures necessary to protect its rights, including initiating a lawsuit against Fox News Channel,” Elias wrote in a letter to the network. “We therefore demand that Fox News Channel take immediate action to preserve all information relating to the Media Matters Surveillance that is in the possession, custody, or control of Fox News Channel, including information held by third parties from whom Fox News Channel could obtain the information or over whom Fox News Channel exercises control.”

Media Matters is similarly prepared to take legal action if necessary against Ailes and 21st Century Fox, according to the letters published in full below.