For our series 'Rape on the Night Shift,' we spent more than a year and a half talking to janitors who said they were assaulted while cleaning hotels, shopping malls and even the San Francisco Ferry Building. These women have been largely invisible to the government agencies in charge of keeping workers safe on the job.

Georgina Hernandez is pouring a glass of juice for her 4-year-old daughter in a tiny apartment near downtown Los Angeles. Racks of colorful blouses and skirts take up most of the living room. She earns extra money selling clothes at swap meets.

“I don’t want to work as a janitor again. It’s a heavy job for us single mothers, because there are a lot of injustices,” she says in Spanish.

Hernandez used to work cleaning a movie theater and a restaurant, scrubbing grease off the floors and kitchen fans. She says sometimes six weeks would go by between paychecks.

“I worked from 11 at night until 11 in the morning. I didn’t have overtime, I didn’t have rest breaks. I worked without stopping,” she says.

Turns out she and her co-workers weren’t even making minimum wage.

“There are many single moms working as janitors who are exploited,” says Hernandez. “And there’s no one asking them, ‘How are you working? How many hours do you work?’ ”

Hernandez moved to another job, cleaning a hotel lobby. And there she faced a different kind of exploitation.

According to court documents filed in a lawsuit against her former employer, Hernandez’s supervisor at the hotel repeatedly pressured her for sex and threatened to fire her if she didn’t respond. The lawsuit claimed he sexually assaulted her in the parking garage where there were no security cameras.

“It was an experience that I don’t wish upon any woman,” she says. “Much less a janitor, working at night.”

Our investigation found that sexual violence -- particularly by male supervisors -- has affected janitors across the nation. From tiny cleaning services to the nation’s biggest janitorial company, ABM.

“No one is saying that these things don't happen. The company is not saying, nor has it ever, that these things don't happen,” says attorney Mary Schultz. She won a major gender discrimination lawsuit against ABM before the company hired her as a consultant for three years to help them improve their policies. Schultz says issues will inevitably arise with such a diverse workforce, spread out across the country.

“Just think of a city. There’s always crime somewhere in the city," says Schultz. "Does that mean if there's a lot of crime in the city the entire city is going to be liable? To say that you know a company is all-knowing, all-seeing and can prevent a crime before it happens, that's not realistic.”

Schultz says the fact that janitors work alone at night complicates the job of ensuring their safety.

“There are limited ways of doing it," she says. "I mean you can't post a federal marshal at the door."

So what is the government’s role? Well, there’s the Equal Employment Opportunity Commission, which can respond to complaints of sexual harassment after the fact. But how about the agencies charged with preventing dangerous conditions at the workplace?

We talked with Jordan Barab, deputy assistant secretary of labor for the federal Occupational Safety and Health Administration.

“So if someone is raped at work, is that considered an unsafe work environment?” I ask.

“Well, clearly, it’s an unsafe environment if someone is raped at work,” says Barab. But when I ask him whether OSHA has ever taken on a case involving rape in the workplace, he says, “Not that I’m aware of.”

According to estimates from the U.S. Department of Justice, about 50 workers a day are sexually assaulted or raped on the job. But OSHA doesn’t have any official standards for preventing workplace violence of any kind, sexual or not.

The agency has issued some voluntary violence-prevention guidelines for some industries like convenience stores, where workers may get held up at gunpoint -- ideas like putting more workers on a shift so employees aren’t alone, or giving them personal alarms. Strategies that might work with janitors.

Until our interview, sexual violence against janitors wasn’t something OSHA had on its radar.

California has its own workplace safety agency, under the California Department of Industrial Relations, or DIR.  It's been looking at abuses in the janitorial industry, but not sexual assault.

"When there is an underground economy, there are many other illegal activities going on," says Christine Baker, DIR's Director. Her agency has been cracking down on janitorial subcontractors operating in the black market.

But, like most labor agencies, they don't have a regular team of nighttime inspectors.

"Janitorial is one of the harder industries to get at the workers," says Baker. "They may have several job sites, may be moving around, they work at night. It is very difficult, and they are many times, non-English speakers."

Four years ago, Baker's department launched a wage theft campaign, and has gone after janitorial companies for more than $15 million in back wages and penalties.

State regulators are working on developing new rules around workplace violence. But it’s unclear whether they’ll include specific language around sexual assault.

PART III: Former Janitors Go Undercover to Clean Up Abuses
So for now, who is working to keep janitors safe? Next we’ll meet a tiny but tenacious band of undercover watchdogs.