Rebekah Brooks and her husband, the horse-trainer Charlie Brooks, were arrested this morning as part of the biggest wave of arrests yet to come out of Operation Weeting, the police investigation into phone hacking in the U.K. press, and specifically into Rupert Murdoch’s former flagship tabloid, News of the World, which closed last summer amid accusations that the paper’s journos had hacked into the cellphone of murdered schoolgirl Milly Dowler. Brooks is a former editor of that newspaper, as well as of The Sun, which has been battered of late by a parallel investigation into illegal payments to public officials.

According to a statement released by Scotland Yard, six people were arrested between the hours of 5 a.m. and 7 a.m. this morning, on suspicion of conspiracy to pervert the course of justice. While police refused to identify the suspects, they confirmed that a 43-year-old woman and a 49-year-old man were both arrested at their homes in Oxfordshire and were being interviewed at Buckinghamshire Police Station. The pair are widely reported to be the Brookses.

Sky News has reported that the head of security at News International, Mark Hanna, is included in the arrests.

In its statement, Scotland Yard said that “a number of the addresses connected to the arrests are being searched.” Twenty-three people have so far been arrested in connection with Operation Weeting, including former chief reporter Neville Thurlbeck and former executive editor Neil Wallis. Cheryl Carter, Rebekah Brooks’s former personal assistant, was previously arrested on suspicion of conspiring to pervert the course of justice, along with Glenn Mulcaire, the infamous private investigator.

Significantly, the arrests are not in relation to the illegal hacking of voicemails or payments to public officials, but to obstructing justice. On that front, there have been some potentially damaging allegations of late. Earlier this year, it was revealed that an IT worker deleted a controversial email from the account of James Murdoch, who stepped down as the head of News International this month, just 11 days before Operation Weeting began. And court documents released last month allege a so-called “email deletion policy” at News International, discussed by at least one unnamed senior executive, in which “hundreds of thousands of emails, on nine separate occasions, were destroyed,” according to the documents.

Conspiracy to pervert the course of justice carries more serious legal implications than phone hacking. Tom Watson, the M.P. leading the campaign against Murdoch in Parliament, responded to news of the email deletion policy last month by tweeting, “the game is up @rupertmurdoch.”

Martin Moore, the director of the Media Standards Trust and founder of the Hacked Off campaign, told The Daily Beast in an email today that today’s arrests could be linked to the deleted emails. “A few weeks ago we learnt that senior executives at News International deleted hundreds of thousands of emails in a deliberate policy to undermine legal action by victims of hacking,” he said. “This was conspiracy to pervert the course of justice on a pretty grand scale. It would not be surprising if today’s arrests were connected to that deletion.”

This is not the first time Murdoch’s flame-haired protégée has been arrested in connection with phone hacking. Last summer, just two days after she had resigned as CEO of News International—the U.K. arm of Murdoch’s News Corporation—she was arrested on suspicion of conspiring to intercept communications and of corrupting police officers.

That same month, Charlie Brooks made headlines when he tried to reclaim a bag containing a computer, paperwork, and a phone that had been discovered in a car-park bin near the couple’s London home. Security guards reportedly handed the bag over to the police. Charlie Brooks denied that the bag belonged to his wife, and his official spokesman, David Wilson, said that the bag contained “nothing to do with Rebekah or the [phone-hacking] case.”

This morning’s arrests come just weeks after police rounded up other journalists from The Sun in relation to alleged illegal payments to public officials. Those arrests were reportedly driven by News International’s own internal management and standards committee, which was created in the wake of News of the World’s closure in order to investigate the hacking allegations, and which has been pouring through a trove of millions of emails and handing pertinent information over to police. However, the Brookses’ arrests come from Scotland Yard’s own investigation and is not tied to the internal investigation.

While Rebekah Brooks had been lying low since her arrest last summer, tabloid interest in her flared up again last month when it was revealed that Brooks and her husband had been loaned a retired horse from the Metropolitan Police to ride at their estate in Oxfordshire. The revelation came just as investigators and the Leveson inquiry had trained their focus on potentially inappropriate ties between journalists and police, and “Horsegate”—as it soon became known—seemed to indicate that Brooks herself may have been receiving favors from Scotland Yard. (The Metropolitan Police said that sending retired horses out to pasture was a common practice.) The scandal snowballed when Prime Minister David Cameron admitted, after days of questioning, that he, too, had ridden the horse, though Cameron insisted that he went riding with Charlie Brooks and not Rebekah herself.

The Horsegate incident revived longstanding scrutiny over the closeness between Cameron and the Brookses—Charlie is one of the prime minister’s friends from his Eton days, and Cameron was so close with Rebekah that he reportedly signed his letters to her “love David.” He attended the couple’s wedding in 2009. Former News of the World deputy Andy Coulson, meanwhile, worked as Cameron’s communications director, resigning last year. With the Brookses now reportedly in police custody, questions over whether the implications from the phone-hacking scandal could lead all the way to Downing Street look likely to intensify. Cameron, who is meeting with U.S. President Barack Obama in Washington, D.C., today, has not commented on the arrests. He is widely expected to be called before the Leveson Inquiry—the public inquiry into the phone-hacking scandal—when the focus turns to the relationship between politicians and the press.