The woman known to British tabloid readers as Wagatha Christie testified Monday about the sleuthing techniques that led to her nickname, saying she posted fake news about herself on social media as a ruse to discover who was leaking stories about her family to the press.

The testimony from Colleen Rooney, wife of English soccer hero Wayne Rooney, came in the fifth day of a libel trial at the High Court in London that pits her against the wife of another soccer star. With the wives and girlfriends of top players known here as WAGs for short, Rooney became known as Wagatha Christie soon after the story of her detective work became headline news. The nickname is a tabloid homage to the detective novelist Agatha Christie.

Rooney posted false information about herself on Instagram after blocking all of her followers except the suspected leaker. Then she waited to see if any of the stories appeared in print — and they did.

“I wanted the story to run so I had evidence,” Rooney testified. “I didn’t want the story out there. I wanted it for my own evidence.”

In October 2019, Rooney publicly revealed that the leaks came from the account of Rebekah Vardy, wife of Leicester City star Jamie Vardy. Rebekah Vardy denied being involved and sued Rooney for libel, triggering a courtroom battle that has reportedly cost each side more than 1 million pounds ($1.2 million) in legal fees.

The case has drawn intense interest in Britain because both women are TV personalities closely watched for their style choices — celebrities on their own besides being married to famous athletes.

Rooney said after the leaks began, she publicized her concerns on Instagram in hopes that whoever was responsible would get the message and stop. When the leaks continued, she launched her “sting operation.”

She said she suspected Vardy because she was “fame hungry” and had reacted suspiciously when Rooney stopped following her on Instagram.

When asked why she didn’t confront Vardy with her suspicions, Rooney said she had already given her the chance to come forward and admit what she was doing.

“I had put warning signs out there and Mrs. Vardy, or whoever was on her account, never came to me and said, ‘It was me that has been passing information onto the Sun,’’’ she said. “At that time I didn’t think she would tell the truth anyway, even if I confronted her.”