The voice mail was from my mother’s longtime stockbroker, in the private-client department at Charles Schwab. “We’ve had some requests for large cash withdrawals from her account,” she said, and asked me to call her back. “We’re afraid that maybe someone has gotten to her. She requested two hundred thousand out.” She’d taken the money from a trust that she inherited from her own mother; now, the broker said, she had requested even more money. “And, again, we just want to make sure that this is legit as to what’s going on.”

I called back immediately and told the person who took my call to stop everything. Then I called my mother, who is in her late eighties and lives alone, in Kansas City, in a retirement community near a shopping area called the Country Club Plaza. (People who aren’t from Kansas City laugh at that name, but the shopping area is almost a century old. There’s also a Country Club Christian Church.) She angrily said that she knew what she was doing, and told me to butt out. Eventually, under pressure, she explained that she’d won enough money to set up our family for life, and that, if I interfered, I would ruin everything.

Back on the phone to Schwab. Then to the local bank where my mother had a checking account. Then e-mails to my daughter’s husband and an old high-school friend (both lawyers). Then phone calls or e-mails to my siblings, the Kansas City Police Department, the F.B.I., my mother’s accountant, and various state and federal fraud-related agencies and departments. That evening, my sister Anne, who’s a psychologist and lives about an hour away from my mother, visited her in her apartment. At that point, my mother still believed that she’d won $3.7 million from Publishers Clearing House, and that she would ultimately be vindicated. So Anne had to argue with her about that while making copies of e-mails and other documents, and retrieving torn-up papers from the trash. She had to pull one of the documents from my mother’s hand. She also took my mother’s checkbooks and credit cards.

The scammer had told my mother that she’d be receiving her millions just as soon as she paid some federal taxes and fees—not directly to the United States Treasury, of course, but to a couple of helpful people whose job is handling that sort of thing. The person she talked to on the phone said his name was Sam. The e-mails that he and his fellow-scammers sent my mom were as sloppy and ungrammatical as the ones you get from Nigeria; in a couple of them, even her own name is misspelled. But she fell for everything. On Sam’s instructions, she shipped four fifty-thousand-dollar checks overnight to an address in California. When I checked her transaction-history page on Schwab’s Web site, I could see three of the checks, which were made out to two names. (The fourth check had not, apparently, been cashable.) It was to one of those names—initials H. C.—that my mother had overnighted everything. H. C. had signed the back of his check and deposited it into an account at Golden 1 Credit Union. I assumed, at first, that the name must be a fake, but, when I searched for it on Google, I found a listing in a Dun & Bradstreet online business directory—and the address was the same one my mother had sent the checks to, in Rancho Cordova, California. There was even a phone number, which I was scared to try. I then plugged the address into Google Earth, and, in Street View, I was able to look into a messy garage: lawnmower; joint-compound bucket; sawhorse; washer and dryer. There was a pickup truck parked in the driveway, across from a portable basketball hoop. The truck was facing out, toward the street, as if ready to make a getaway.

Everyone’s first reaction is incredulity. How could even an elderly widow have believed something so obviously phony? Actually, though, my mother was no more gullible than other people, without whose coöperation the theft could not have occurred. Fooling my mother required several apparently experienced criminals working in concert, but fooling Schwab and her accountant required only her. My mother had a stroke in 2013. (She drove herself to the emergency room.) Now she was about to turn eighty-nine, and, suddenly, she was asking to make transactions that were radically different from any that she’d made before. Before I’d listened to half of the voice mail from the broker—before she had mentioned any sum of money—my stomach had tightened into a knot, and I knew for certain that my mother had been scammed. Why didn’t Schwab? And, if the broker was suspicious enough to call me before allowing my mother to make a second huge withdrawal, why not before allowing her to make the first? The senior-fraud page of the F.B.I.’s Web site says, “People who grew up in the 1930s, 1940s, and 1950s were generally raised to be polite and trusting.” But tottering oldsters aren’t the only vulnerable people in the world. How could trained financial professionals have believed the lies of someone who lies as badly as my mother does?

On a cops-and-robbers television show, discovering that H. C. was a real person with a real house and a real bank account wouldn’t have been as easy as it was for me—there would have been a hard drive buried in a landfill, or DNA on a soda straw, or a grainy photograph that could be deciphered only with a supercomputer—and finding him would have been a break in the case. Not so in real life. Four days after I filed an online report with the State of Missouri—which claims to be extremely interested in wiping out elder fraud—my mother received a letter from a paralegal in the office of the Secretary of State saying that an investigator had reviewed the matter and that “no further investigation will be conducted by this office.” The only law-enforcement person who called me was a detective in the economic-crimes section of the Kansas City Police Department. He said that the people who receive the money in cases like this are usually at least semi-unwitting participants, who pass the money to someone else, who wires it out of the country. He did say that it was unusual for paper checks to be involved, because scammers, for obvious reasons, prefer bank transfers. I interpreted this fact as a reason for mild optimism. But he didn’t let out a Sherlockian “Hello! What’s this?” when I told him I had a photograph of the inside of H. C.’s garage. He said that Anne should go to any police station in Kansas City and make a report. “And tell her not to leave without a case number.”

At the police station, Anne had trouble getting anyone to pay attention to her. She eventually did speak with an officer, in a cavernous lobby with echoing acoustics. The officer sat at a long table on the other side of a thick glass partition, which, Anne told me later, in an e-mail, “had four places to speak into a little round metal louvered hole (about six inches too high) and four little scooped-out slots like where they slide you your cigarettes at the after-hours gas station.” Through that slot, she gave the officer a copy of a form I’d filed on the Web site of the federal government’s Internet Crime Complaint Center, to which I’d been referred by an F.B.I. agent. She said the form contained all the information he needed. “He looked at it briefly, then slid it back to me, and said, ‘This is for another investigation.’ Then he pulled out a tiny spiral notebook, the kind you might make a shopping list in, and began slowly writing things down.” Anne had made a copy of the address label my mother took to the UPS store when she sent the checks to H. C., but he didn’t want to see it. “We’ll need to have all the originals, for evidence,” he said. When he had finished writing in his tiny notebook, he told her that another officer would contact her in a day or two. (She heard back a month later.)