In 2015, Representative Adam Kinzinger had an unusual visitor at his constituent office inside a bus station in Rockford, Ill. A woman from India had flown to meet Mr. Kinzinger, claiming that she had developed a relationship with him on Facebook.
“She waited around in that bus station for two weeks for me to show up, and I didn’t,” he said in an interview. “She’s a poor lady, too. It took all her money to fly from India to me.”
The episode was just one of the bizarre interactions that Mr. Kinzinger said he had had over the past decade with women around the world who believed they were dating him.
That is because Mr. Kinzinger, a Republican and a lieutenant colonel in the Air National Guard, is one of what are probably thousands of United States service members who have been ensnared in a widespread fraud that has played out for years on Facebook, Instagram and other social networks and dating sites. Swindlers impersonate service members online to lure victims into false romances and then cheat the victims out of their savings.
Mr. Kinzinger said he was moved to take action after reading about the scope of the schemes in a New York Times article this week. On Wednesday, he sent a letter to Mark Zuckerberg, Facebook’s chief executive, requesting more information about what the company was doing to prevent such fraud on its sites.
“There needs to be accountability for this issue that can, quite frankly, destroy lives,” Mr. Kinzinger wrote in the letter. “Facebook has an immensely significant role to play in getting this situation under control.”
In an interview, Mr. Kinzinger said he was also in the early stages of preparing legislation that would force social-media companies to do more to fight the problem.
“There has to be a place for government to step in and have penalties,” he said. “I don’t know exactly what that looks like yet, but it has to be something.”
Mr. Kinzinger said he needed more time to study the issue before publicly discussing specific legislation. He mentioned several things Facebook could potentially do to stop scammers, including using facial recognition software to automatically spot impostors and requiring identification to create an account.
A Facebook spokeswoman said that the company was reviewing Mr. Kinzinger’s letter and that it looked forward to answering his questions. Facebook has previously said that it used software and human reviewers to remove impostor accounts when it found them, and that it worked with law enforcement authorities to prosecute scammers. The company said it was investing in new technology to better combat fraud.
Facebook estimates it has 120 million fake accounts. Instagram, which Facebook owns, does not disclose a figure for such accounts.
A bill from Mr. Kinzinger would be the latest effort in Washington to increase regulation of the largest technology companies. The Justice Department and the Federal Trade Commission are investigating antitrust complaints against them, and the House Judiciary Committee is examining accusations that they engage in anticompetitive behavior. There is also new legislation that targets Silicon Valley, including a bill proposed this week by Senator Josh Hawley, Republican of Missouri, to curb social-media addiction.
On Thursday, Senator Mark Warner, Democrat of Virginia, said The Times’s article about military romance scams showed that Facebook had a lot of work to do to address the various problems on its sites.
“We continue to see that despite a lot of public pledges to address core problems with its platform, Facebook still remains incredibly vulnerable to exploitation by bad actors,” Mr. Warner said in a statement. Before it pursues new projects like its proposed cryptocurrency, Libra, he added, “Facebook should first focus on fixing the serious problems that remain with its platform, as these abuses illustrate.”
Mr. Kinzinger, who was stationed in Iraq twice as an Air Force pilot, said that he had begun dealing with online impostors around 2008, and that they had been a persistent headache since.
“It’s literally been an 11-year battle with this, and there’s nothing you can do about it,” he said. “It’s devastating.”
Mr. Kinzinger said dozens of women had contacted him or members of his staff to say they were in a relationship with him. A second woman from India reported sending one of the impostors roughly $10,000, he said. A woman from Arizona sent his staff members screenshots of her explicit online chats with a person posing as Mr. Kinzinger, worrying him that he was the victim of a political attack.
“These women talk to you like they’ve known you for a year, and I have no idea who they even are,” he said. “We turn these into Facebook, Instagram and Capitol Police, and there’s nothing they can do about it.”
Mr. Kinzinger said some of the impostor accounts impersonated him to run other frauds. Members of his staff recently communicated with one such account on Instagram purporting to be Mr. Kinzinger’s “private account which I use to communicate with my parents family and friends,” according to screenshots the staff members provided to The Times. Whoever was behind the account described needing help handling a briefcase with an enormous sum of money, saying: “That’s why i am looking for a trust worthy person.”
[Get the Bits newsletter for the latest from Silicon Valley and the technology industry.]
When Mr. Zuckerberg testified before Congress in April 2018, Mr. Kinzinger told him that just before the hearing he had found another Facebook impostor: a profile for an Andrew Kinzinger who lived in Los Angeles and used photos of the congressman. He asked Mr. Zuckerberg what Facebook was doing to combat such fake accounts.
“Long term, the solution here is to build more A.I. tools that find patterns of people using the services that no real person would do,” Mr. Zuckerberg replied, adding such technology had led to the removal of tens of thousands of fake accounts. “That’s an area where we should be able to extend that work and develop more A.I. tools and do this more broadly.”
Mr. Kinzinger said members of his staff frequently scanned social media for impostor accounts and reported any that they found. A search by The Times on Wednesday yielded just one impostor account on Instagram that used Mr. Kinzinger’s exact name, although it had no photos or followers. Mr. Kinzinger said that many accounts used his photos under a different name and that they were difficult to find.
He said one seemingly simple fix would be for Facebook to notify users when other accounts used their photos.
In late 2017, Facebook said it would do just that, but recent tests by The Times showed that the feature often did not work. A Facebook spokeswoman said last week that impostors also needed to exhibit suspicious behavior for the company to notify the apparent subjects of impersonation, a detail it did not include in its announcement of the technology.
Follow Jack Nicas on Twitter: @jacknicas.