WASHINGTON - The first man who knocked on the Fauquier County, Va., woman's door told her they had been emailing and he was there for sex. Shocked and perplexed because they hadn't corresponded, the woman sent him away.

But the men kept coming. They arrived on her doorstep as many as six times a day, sometimes traveling from other states. One had a crowbar. Others refused to leave. Another rammed his car through a security gate that she installed.

In all, there were about 100. Each said he had communicated with her. All expected sex.

The unrelenting onslaught was allegedly organized by an angry ex-boyfriend, who had assumed the woman's identity online and crowdsourced his harassment to dozens of unwitting accomplices he lured to her home, prosecutors say in court papers.

The case, which goes to trial next month in federal court in Virginia, is among a number around the country in which stalkers are accused of stealing their victim's online persona and using the power of social media as a weapon.

The Fauquier County woman believed it was only a matter of time before she was assaulted, raped - or worse. She turned her home into a fortress with security cameras, floodlights and a gate.

"I live in fear of anyone coming to my door," said the woman. "I'm a prisoner in my own home."

For a Prince George's County, Md., woman, the nightmare began the same way - with a knock at the door.

The man on her doorstep last June told her she had invited him over for sex during an instant message chat, according to court documents. She had no idea what he was talking about and told him she was not interested.

The 33-year-old mother of four had divorced Michael Anthony Johnson II, an unemployed computer specialist from Hyattsville, Md., in 2011. Their relationship was tempestuous.

Johnson went to her home one night in 2011, got in her car and waited for her until the next morning. When she got in, Johnson wrapped his hands around her neck. She escaped, and Johnson was convicted of assault.

Now, she believed Johnson had her in his sights again. When she logged onto Craigslist in the days after the man showed up at her home, she found ad after ad. They had increasingly vile titles including one that read: "Rape Me and My Daughters."

When she clicked on the ad, her photo popped up and her address was listed.

"My stomach just went into a knot," the woman said.

Experts say Internet impersonation remains rare, but recent cases have prompted about a half-dozen states including Texas, New York and California to pass laws criminalizing it. Maryland and Virginia are not among them.

In Texas, two Hood County middle school students were arrested in 2012 for creating a fake Facebook profile for a fellow student and using it to threaten other students. In 2011, a 22-year-old Los Angeles man was convicted of creating at least 130 fake social media accounts to harass his former girlfriend.

To combat the problem, Facebook has created a reporting system to flag fake accounts. Craigslist did not respond to repeated requests for comment.

Hemanshu Nigam, a former federal prosecutor who handled computer crimes and founder of Internet security company SSP Blue, said Internet impersonation stalking will probably only increase as more people become comfortable with social media.

He believes the Internet has also emboldened some stalkers.

"They are using the anonymity of the Internet to do things they would never do offline," Nigam said.

The Fauquier County woman's tormentor used Craigslist, too. Kenneth Kuban is accused of posting salacious ads posing as the woman in the "Casual Encounters" section. One read:

"I'm a senior lady who is looking for some fun

"And adventure in my life!! Would like to meet a gentleman in his 50s that... can give me some pleasuring."

The woman said the ad and at least 50 others were posted between January and March 2012. She flagged them as inappropriate, but it sometimes took two days for Craigslist to remove them.

It did little to slow the flow of men to her door. They came from as far away as North Carolina and West Virginia. The woman called the Fauquier County Sheriff's Office to chase them away - sometimes several times a day.