Until last summer, pretty much anyone buying or selling sex in the San Francisco Bay Area used myRedBook.com. For more than a decade, the site commonly referred to as RedBook served as a vast catalog of carnal services, a mashup of Craigslist, Yelp, and Usenet where sex workers and hundreds of thousands of their customers could connect, converse, and make arrangements for commercial sex. RedBook tapped into the persistent, age-old, bottomless appetite for prostitution and made it safer and more civilized. The site was efficient, well stocked, and probably too successful for its own good.

Launched in 1999 by a Mountain View, California, tech entrepreneur named Eric “Red” Omuro, RedBook began as a modest hub for mongers (Internet slang for johns) to discuss the local scene and post reviews of escorts. As it grew, the site expanded beyond the Bay Area, adding sections for Southern California, the Central Coast, Phoenix, Nevada, and the Pacific Northwest. Omuro also added a key functionality—he made it possible for sex workers to advertise their services.

RedBook may have been full of racy talk and the promise of erotic assignations, but the site itself was anything but sexy. Its ugly, bare-bones design was straight out of the early 2000s. It resembled a web page you might use to find a new job or a secondhand bike. If you were careful to stay away from the sections where photos automatically displayed, you could easily browse potential sex partners at work and your coworkers would never suspect a thing.

Victor Cobo

RedBook was made up of three main elements. The site's naughty classifieds section contained the sort of ads that used to be the sole domain of alt weeklies' back pages: “*College Girl Gone Wild* (BUSTY SMART BLONDE),” “Sexy & Sweet Asian Here to Please Your Needs,” and “Morning $pecials Daddy Let Me Blow Your Mind.” While ads were free to post, advertisers could opt to pay for premium placement.

Then there were dozens of message boards. While the site's most popular forums had names like “Escort 411,” “Street Action,” and “Domination Station,” RedBook also hosted conversations on topics ranging from baseball to bondage, music to massage parlors. Bruce Boston, a data scientist who works for one of Silicon Valley's major tech companies, initially came to the site to find out which strip clubs had the best dancers. He ended up sticking around for four years to join what he describes as the intelligent, provocative, and honest conversations on the site's forums. “It was great,” he says. “You could have an open discussion about your beliefs and thoughts.” Boston participated in conversations on RedBook about everything from Libertarian politics to swinger sex parties.

But the most valuable part of the site was its reviews section. You could pay $13 a month for access to the section, where VIP customers shared detailed write-ups of their experiences with escorts, BDSM providers, and erotic masseuses. As part of their reviews, users listed the services they received, as well as details about the provider's physical attributes. Looking for a well-reviewed Latina under 30 who provides full-body sensual massage in Oakland? Just filter to narrow down your search.

Then, on June 25, 2014, visitors to RedBook got a rude shock. Instead of a directory of links to sexy ads, forums, and reviews, they saw a dire-looking alert from the Department of Justice, FBI, and IRS stating that RedBook's domain had been seized. The Feds' message, still up today, asserts that there is probable cause that the site was involved in “money laundering derived from racketeering based on prostitution.”

Federal agents arrested Omuro, 54, along with Annmarie Lanoce, a 41-year-old bespectacled mother from Rocklin, California, a suburb of Sacramento. (Lanoce worked for Omuro, helping to moderate RedBook and manage its operations.) Their homes were raided and their computer equipment confiscated. In July, Omuro was charged with using the Internet to facilitate prostitution and 24 counts of money laundering. Lanoce was charged with using the Internet to facilitate prostitution. Released on bond, they were prohibited from going online or associating with former users of the site.

The United States attorney's indictment against Omuro claims he took in more than $5 million. The site brought in revenue from fees paid by RedBook users for access to the site's enhanced features. It's unclear why the authorities targeted RedBook and not the array of other sites where sex is openly bought and sold. The US attorney's office declined to offer any comment, but its indictment speaks for itself.

Both Omuro and Lanoce initially pleaded not guilty to all charges, but in November Lanoce changed her plea in the hope that it might allow her to avoid a felony sentence in exchange for good behavior. A few weeks later Omuro followed suit and entered his own guilty plea to the charge of using the Internet with the intent to facilitate prostitution, agreeing to forfeit nearly $1.3 million in cash and property. Omuro's guilty plea marked the first-ever federal conviction of a website operator for the crime of facilitating prostitution. Both Omuro and Lanoce are due in court in March for sentencing.

Photographer Victor Cobo has been shooting images of sex workers in San Francisco's Tenderloin district for more than 15 years. Victor Cobo

San Francisco's gritty Tenderloin district is bordered by touristy Union Square on one side and tony Nob Hill on another. In 2012 Twitter installed its lavish new headquarters in an old art deco building on Market Street, kicking off a surge of corporate moves to the area by the likes of Uber, Spotify, Yammer, and Square. In turn, hundreds of young tech workers have recently relocated to the Tenderloin and are rapidly changing the economics of a neighborhood that has managed to resist gentrification for decades.

That resistance is on full display one afternoon this fall when I take a short walk around the neighborhood. I count five women standing on various corners, some actively waving at cars, others more carefully making low-key eye contact with male drivers as they cruise by. One woman is particularly aggressive. She wears a black tank top with spaghetti straps, mommish jeans, and a San Francisco Giants sweatshirt tied around her waist. You might mistake her for a lady on her way out to buy groceries, except she's wearing cartoonishly thick lipstick and heavy eye makeup, especially striking in the middle of the day.

I stand about 10 feet from her, near a bus stop. A guy on a Harley stops at a red light, and the woman lewdly thrusts her hips in his direction. The biker rides on, and a police truck pulls up alongside us. The cop in the passenger seat calls her over. She walks toward the car and leans her head into his open window. The officer says something quietly to her, and she walks back to her post. A beat later, the cops are gone, and she continues to hail passersby—just a little more subtly now.

The 38-Geary bus pulls up, lets out a dozen passengers, and picks up a few new ones. When I don't get on the bus, the woman knows I'm not there waiting for a ride downtown. She looks over to me. “Hey. My name's Cathy,” she says. “What are you doing today?”

I get flustered and begin to stammer, then manage to blurt out that I'd just come from a meeting and that I'm trying to figure out what to do next.

“You need company?”

I tell her no, I'm good. I step off the curb and quickly cross illegally in the middle of the street. Then I turn back. “Hey,” I say to Cathy. “Can I find you on the Internet?”

“Nah,” she says. “I used to get RedBook reviews, but they took it down.”

Omuro started Redbook so that Bay Area mongers would have a home on the web. It succeeded, ultimately attracting so many users that the site became a full-fledged business, with massive profits. But when RedBook was shut down, the people who were hit the hardest weren't the buyers, but the sellers—sex workers like Cathy for whom the site had made the world's oldest profession significantly less risky.

One of the ways the site reduced danger for workers was by making it easier for them to weed out bad dates, from poor tippers to full-on abusive creeps. Providers could choose to meet only customers who were well known and well liked on RedBook's forums, and some workers even required references from other escorts on the site before taking on a new client. “RedBook provided a space to safely negotiate and screen clients that reduced the likelihood of being victimized by predators or cops,” says Kristina Dolgin of the Sex Workers Outreach Project, a national advocacy group.

RedBook may be gone, but the migration of the sex trade from the streets to the Internet is only accelerating. Some sex workers use social media to advertise (search Twitter for some combination of the city you're in, and #escort, #incall, or whatever kink you're into). Others have their own websites, often built using specialized services like Escort Design—a kind of WordPress for people in the sex industry. But the most common way to connect with clients online is through sites similar to RedBook that have yet to be shut down by the authorities. Scott Cunningham, a Baylor University economics professor who studies prostitution and black markets on the web, says that while exact figures are unknown—no national census has been conducted—he has no doubt that the vast majority of today's paid sex arrangements originate through the Internet. “Sites like these, and the Internet more generally, have taken most of the action off of the street,” he says. “It's likely that these websites have actually expanded the market.”

Victor Cobo

If sex workers simply want to buy an ad, they can still use Cityvibe, Lovings, Backpage, and Eros Guide. RedBook was different, in that its vast network of message boards made it possible for workers to not only advertise but ask questions of one another, find support, and even make friends. This is one of the things that Siouxsie Q, a sex worker in Oakland, misses most about RedBook. “We lost a critical resource for building community,” she says. “And building community is already tough enough when you've been marginalized and your work is criminalized.” Women used RedBook's forums to share everything from jokes to medical and financial tips that were useful to people in the sex industry, she says.

Siouxsie's career in sex work is as diverse as it gets. In addition to seeing a few clients each week for escort and domination services, she writes a sex column for SF Weekly, teaches sex classes for couples looking to add spice to their love lives (one of her recent courses was called Monogamaybe), models for fetish websites, and stars in adult films. She was recently nominated for an AVN—the Oscars of porn.

She also hosts and produces two podcasts. The Whorecast focuses on the people and politics of sex work—a recent episode featured an interview with a marine who says his side gig as a porn performer cost him his pension. (The Whorecast was originally titled This American Whore, but a statement from This American Life's Ira Glass convinced Siouxsie to change the name.) Her other podcast is about Game of Thrones from the perspective of two sex workers. It's called Winter Is Coming … On Your Face.

But escorting remains a primary source of Siouxsie's income. And since RedBook was shut down, her business has taken a substantial hit. “I've had immense trouble connecting with new clients,” she says. “I have only taken on two or three new people since the site closed, which is a huge drop.” She blames the loss of the site's massive traffic and reviews section, which was useful in helping clients find dates. Guys can still get Siouxsie's contact information through her personal website, but all the positive comments that clients wrote about her over the years vanished from the web the moment RedBook was pulled offline. “Imagine you have a restaurant with a ton of great reviews on Yelp, and then Yelp gets shut down,” Siouxsie says. “All that information is gone, and now it's hard for people to find out about your restaurant.”

THE REDBOOK CLIENTS WERE NICE, “NERDY, TO BE HONEST.” NOW RACHEL HAS TO DO MORE CAR DATES.

SHE HATES CAR DATES.

By closing down RedBook, law enforcement made it tough for specialty escorts like Siouxsie to set favorable rates for their services. “Five or six years ago, a bunch of women on the site who did erotic massage got together and were like, ‘What if we all raise our rates by $20?’ And it totally worked. That can't happen now.”

Then there's the reality that so much of the sex workers' personal information is now in the hands of the authorities. “It's likely that law enforcement agencies now have people's IP addresses, email addresses that might include their real names, and credit card information,” says Nadia Kayyali, a staff activist for the Electronic Frontier Foundation. “And one of the trends we've seen lately is that everything they get, they keep. It goes into a database somewhere.” The fear is that the sex workers could be surveilled and possibly arrested at any time.

In the wake of RedBook's shutdown, Kayyali set up a workshop, held in an unpublicized location in San Francisco, to teach sex workers how to anonymize their online communications and transactions. She explained to about 20 women the basics of the Tor browser and offered tips for improving password security. The attendees' questions were smart and informed, and she was impressed by the amount of thoughtfulness in the room. “There are sex workers with PhDs,” she says. “There are sex workers who know how to code.”

Then again, the people who are most likely to be targeted by police are those with the least amount of experience with technology. “They're working on the street and probably operating mostly with phones,” Kayyali says. So at her training session she also talked about the importance of basic security measures like using passcodes and text message encryption. “They're relatively simple things but can provide some measure of security on the street,” she says. “And that's more important than ever—we're seeing more workers out on the streets now because of the closure of RedBook.”

At least in the short term. Cunningham, the Baylor economist, points to a study he coauthored in 2011, which suggests that the Internet may have decreased the number of sex workers age 25 to 40 who work on the street.

Since RedBook closed, "I've had immense trouble connecting with new clients," says Siouxsie Q. Victor Cobo

One woman who relied on RedBook's free ad listings calls herself Rachel, a 45-year-old sex worker who's been operating in the streets and residential hotels of San Francisco's Tenderloin district for the better part of 20 years. She's a longtime crack addict and often homeless, but today she's neat, clean, and fashionably dressed in a slouchy sweater, leggings, and new cowboy boots. If you walked by her on the street, you'd never guess what she did for money.

After a few minutes of conversation on the corner of Post and Hyde and negotiation of a $60 fee for her time, Rachel is leading me by the hand past a firehouse, a medical weed clinic, and a drag bar. She breaks away to talk to three guys across the street. After a minute, she pockets a small baggie from one of the men, hugs him, and runs back to me. She grabs my hand again and pulls me toward the front step of the America Hotel, one of the dozens of single-room-occupancy hotels that house the Tenderloin's poor. We walk past a gate and up a filthy flight of carpeted steps to meet a man sitting behind a thick plastic wall with a head-sized hole cut out toward the bottom. He nods at Rachel and glares at me.

“Papa, this is my friend,” Rachel says. The clerk is in his early fifties, wearing a black hooded sweatshirt with the YouTube logo embroidered across the front. He asks me for $10 and tells me that I need to leave a photo ID with him while I'm visiting.

Rachel and I climb another two flights of stairs and arrive at her room. There isn't enough stuff inside for it to qualify as a mess. But it does not feel clean. There's a bare twin-size mattress, a sink, and a dresser with an old TV playing an episode of The Big Bang Theory. There are two duffel bags in the corner near the window. Rachel's clothes and toiletries spill out of them.

She tells me that she moved to the Bay Area from the East Coast in the early '90s and quickly got a gig stripping at the now-shuttered Market Street Cinema. “I'd danced in other places before, and let's just say that the Market Street job was ‘stripping plus,’” she laughs.

Victor Cobo

Rachel pulls an old Lenovo laptop out of her oversize leopard-print purse and shows me an ad for her services that she placed on Lovings, which caters to escorts, sensual massage therapists, and others providing erotic services in San Francisco. She's a new user on the site and paid $120 for the ad to run for a month. Rachel says one of her customers let her use his credit card to pay for it.

She tells me that while she always had a steady stream of calls from guys on RedBook, she hasn't had many responses to her Lovings ad. I browse around on the site, and it's not hard to see why her post hasn't taken off. Most of the women advertising on Lovings appear to be significantly younger than Rachel. Also, their photos were shot by pros, or at least by friends with decent SLRs and basic Photoshop skills. In contrast, Rachel's photos look like cruddy phone pics taken in a squalid hotel room.

“It's been like starting over,” she says of RedBook's shutdown. For years most of her clients were guys on RedBook who got her phone number through other users in the forums, “guys who knew me and could vouch for me,” she says. Although she did encounter a few jerks over the years, she says, she almost always had good experiences with the men she met through the site. “They were nice and normally kind of shy,” she says. “Nerdy, to be honest.”

Recently Rachel's customers have tended to be men she meets offline, guys just milling about or driving around the neighborhood, looking for action. She doesn't like walking the streets, because it's tiring and scary, and she especially hates doing car dates because they're dangerous. But the reality is that she's had to do more of both since RedBook closed. “I still have a couple friends from the site who get in touch, but not many,” she says. “I hope another RedBook comes around at some point. It made life a lot easier.”

WIRED community director ERIC STEUER (@ericsteuer) interviewed Roman Mars for issue 23.02.

Photography by Victor Cobo