WASHINGTON — Sen. Claire McCaskill of Missouri is among a growing number of web-savvy lawmakers who use social media to start casework files for constituents who request help with veterans benefits, Social Security claims or immigration problems — and sometimes even just tours in Washington.

But as Americans become accustomed to “friending” politicians online and tweeting them directly, they should be cautious, McCaskill warns.

The Democratic senator recently became alarmed about the potential for fraudsters to impersonate lawmakers on social media when a woman called her office to inquire about what had happened to $500 she’d supposedly wired to McCaskill.

It turned out someone had created a fake Facebook account using McCaskill’s name and image and used it to solicit money.

“While Facebook and Twitter are great avenues for Missourians to get in touch with me, I want to spread the word that they should make sure it’s really me they’re contacting,” McCaskill said in a statement.

McCaskill was especially irked that a scam apparently was committed in her name because she has cultivated a reputation on Capitol Hill as a consumer protection advocate.

As former chairwoman of the consumer protection subcommittee and the top-ranking Democrat on the Senate Aging Committee, McCaskill has held hearings and led investigations on everything from fraudulent robocalls and weight-loss scams to undisclosed hotel fees and tax refund theft.

She even has a “Submit Your Scam” button on her official website, McCaskill.senate.gov, where Missourians report potential scams to the senator and her staff.

The woman fooled by the senator’s fake Facebook page had communicated via Messenger with the scammers, who falsely claimed to represent McCaskill. They apparently persuaded her that she would become eligible for federal grants if she wired them money.

The woman sent two payments of $250 before calling McCaskill’s office.

Staffers immediately realized the woman had been scammed. It’s illegal for lawmakers to request money in exchange for grants or services.

The only exception is if a constituent wanted to order a flag to be flown over the Capitol, said McCaskill spokesman John LaBombard. In that case, he said, the money would go to the purchase of the flag itself.

McCaskill’s staff urged the woman to contact her local law enforcement while they notified Capitol Police and Facebook.

Facebook soon shut down the fake page. But a search by the senator’s staff turned up several more fake McCaskill accounts, as well as fraudulent accounts from other senators.

“This seems like a problem that is not just affecting us,” LaBombard said.

A couple of fake Twitter accounts popped up this year for McCaskill’s Republican colleague, Sen. Roy Blunt, said his spokesman Brian Hart. The handles replicated Blunt’s official account, but Twitter shut them down soon after staffers discovered them.

It isn’t always clear whether fake accounts are intended for use by scammers, to build followers for ad revenue or are created by political opposition to mimic a candidate and then go negative €” a familiar tactic similar to the creation of phony campaign websites.

It’s important to distinguish fake political social media accounts created to scam people from blatantly fake accounts created to make political points, said Chris Lewis, vice president of Public Knowledge, an advocacy group focused on technology policy.

“Satire has a place in critique and political speech,” he said in an interview. “Fraud does not.”

People should take advantage of the verification tools provided by social media companies to confirm whether a politician’s social media account is real, Lewis said.

It’s also smart to reach out and confirm with a lawmaker’s office or campaign before sending money or sharing personal information online, he said.

“Doing that by phone is probably the safest,” Lewis said. “They have staff dedicated to constituent services, so even if they are contacting you through social media, you should be able to call the office and confirm that person works for them.”

Voters are coming to expect more direct interaction with their representatives online, especially as younger politicians who have grown up with the internet begin getting elected, he said.

That’s why it’s important to realize that social media platforms are tools that take some skepticism and skills to navigate, Lewis said, especially if you want to give money or be more active with a candidate.

“These are great tools to cut through the distance from Washington to the district back home or the state back home,” he said. “You hate to lose that because of people who are defrauding folks.”