LONDON — Coleen Rooney has largely lived in the shadow of her far more famous husband, Wayne, a soccer star who played for one of the world’s biggest clubs, Manchester United, and anchored England’s national team for a decade.
Though Ms. Rooney is not an infrequent presence in the British tabloids, she revealed a different side of herself on Wednesday: a detective who ran her own sting operation to expose the person who had betrayed details about her family life to one of those tabloids.
Her investigation, as detailed in a post on her Instagram account, came with another twist: Her betrayer appeared to be an account belonging to Rebekah Vardy, the wife of Jamie Vardy, a Premier League star who also has played for the English national team.
“For a few years now someone who I trusted to follow me on my personal Instagram account has constantly been informing The SUN newspaper of my private posts and stories,” wrote Ms. Rooney. She will soon return to Britain from the United States with her husband, who will leave his American club, D.C. United, to join Derby County in the second tier of English soccer, after the Major League Soccer playoffs.
Ms. Vardy responded in kind, with a post on Twitter. She denied speaking to journalists about Ms. Rooney, hinted that she had been hacked, and, finally, expressed regret that this had happened “especially when I’m heavily pregnant.”
Ms. Rooney’s revelation apparently had been in the works for months. Having realized that something was amiss as details about her private life that could only have come from someone close to her were being reported in the tabloids, she had come up with a plan to unmask the spy.
She would restrict access to the Instagram Stories section of her private account — separate from her public Instagram account — for every account but that of Ms. Vardy, her prime suspect in the case, and then post several false stories to see what happened.
Among the stories that appeared over the past few months that Ms. Rooney now says were inventions:
She and her husband so desperately wanted their fifth child to be a girl that they traveled to Mexico for a $10,000 “gender selection treatment.” (“Coleen loves her boys more than anything, but she’s never been shy about admitting she would also love a daughter,” the article said, citing only “a source.” “That would really complete the set for her and Wayne.”)
She was planning to revive her television career. The Sun’s article said that she had been forced to turn down a chance to appear on “Strictly Come Dancing” — the British equivalent of “Dancing With the Stars” — and, again citing an unnamed source, said that plans were in place for her to get her own show on Channel 4 or ITV.
The Rooneys’ new house near Manchester, estimated to be worth $25 million, had flooded. The Sun quoted its source as saying, “The house is Wayne and Coleen’s dream, so to see it being damaged has been horrible for them.”
On Wednesday, The Sun added a note to each of those articles online saying that Ms. Rooney “said that she made this story up in an effort to find out who was leaking to the press.”
The disclaimers link to The Sun’s own coverage of the dispute, which asserts that Ms. Rooney had been offered an opportunity to comment on each story before publication, and had declined. “Like all reputable media organizations, we don’t comment on sources,” an anonymous representative of the paper is quoted as saying.
The Sun did not respond to a request for further comment.
“It’s been tough keeping it to myself and not making any comment at all,” Ms. Rooney wrote on Instagram, “especially when the stories have been leaked, however, I had to. Now I know for certain which account / individual it’s come from.”
She acknowledged that followers of her stories may have been slightly mystified by the absence of new posts, but Wednesday’s posting quickly become a sensation online, as outsiders alternately delighted in the back and forth and marveled at the detective work. The term #WAGathaChristie — a nod to the shorthand given to the circus atmosphere that used to surround the wives and girlfriends of the players on the English national team — was soon trending on Twitter in Britain.
And, coming a day after numerous British news outlets cited anonymous sources portraying the German government and the European Union in a bad light as the Brexit negotiations took another turn for the worse, some observers suggested that Ms. Rooney might be the one to find out who was talking. (Many political commentators regard that as a potentially less challenging mystery.)
Another poster on Twitter, mindful of the cloak-and-dagger nature of the drama, imagined Ms. Rooney as the central player in a John le Carré novel.
Ellis Cashmore, an honorary professor of sociology at Aston University in Birmingham, England, said in an email that the situation was almost Shakespearean, taking into account the various elements — “ love, tragedy, deception and, of course, power” — and involving soccer, by far the most popular sport in Europe.
“The story is both trite and profound,” he wrote. “This one invokes some larger questions about the role of the media, the preparedness of audiences to consume this as genuine news, the boundaries between public and private lives of the famous, and the power of media to influence the cultural topography.”
“Oh, and soccer.”
On Wednesday, Ms. Vardy insisted that she would never tattle. “I’m not being funny but I don’t need the money, what would I gain from selling stories on you,” she wrote. “I’m disgusted that I’m even having to deny this.”
Her letter closed with a broken-heart emoji.