The scammer who catfished MPs and their Westminster staff had been active for almost a year.
The targets, who were all male, were sent flirty WhatsApp texts from either "Abi" or "Charlie", depending on their sexuality - with some later being sent explicit photos. At least two MPs are thought to have responded with X-rated snaps of themselves, leaving them open to blackmail and manipulation.
The number for "Abi" is no longer active, but was first reported as a "catfish" - someone online pretending to be someone else - almost a year ago on reverse lookup website Who-Called. More than 100 searches of the number have been made on the site since May last year. Five users left warnings about it, with the most recent just two weeks ago. One reported "a bloke pretending to be a girl" while others specified "a WhatsApp person impersonating a woman called Abi".
When using the name Abi, the scammer sent a picture taken at Whitby Abbey, of a young woman photographed from the back and leaping in the air, her hair flowing. There is no suggestion the woman in the image is actually the scammer.
The number used for the profile is registered to Dutch firm Tismi, which lets people set up virtual numbers for privacy reasons at a fraction of the cost of a SIM. The 13 politicians and others working at Westminster known to have been targets include Tory and Labour MPs, political staffers and journalist.
Sources say the sender appeared to have an insider's knowledge of Westminster, giving chats authenticity by referring to locations, campaigns and events.
Tory MP Luke Evans - sent explicit snaps by "Abi" - alerted Leicestershire Police last month. And fellow Tory MP William Wragg admitted on Thursday that he had been blackmailed to give phone numbers after sending compromising images to the scammer. But some of the confirmed targets did not know the MP, suggesting more than one source may have given out senior politicians' personal details.
Scotland Yard confirmed on Friday they were looking into the scam, adding: "We are working closely with other forces and are in contact with colleagues in Parliamentary Security."
Mr Wragg, MP for Hazel Grove, Gtr Manchester, told the Times newspaper he was sorry for his "weakness", and causing hurt to others.
Today, political journalist Harry Yorke revealed he too had been targeted, though in his case "Charlie" was posing as a woman. Writing in the Sunday Times, he said the scammer had used a picture of a "smiling brunette" who claimed to have met and flirted with him in a Westminster pub. And after a few messages the scammer sent him a "view once" photo, which he did not open.
He informed the scammer that he was married and not interested, but did not report the incident.