I never expected to have to go to the police because of Facebook.
I'm an avid user, checking in multiple times per day, but like most people, I thought of it as a lark—a place to let friends know about minor achievements and grievances, share pictures, and reconnect with acquaintances. And it was – until someone threatened my then three-year old daughter.
It wasn't a stranger. In fact, it was someone on my friend's list – the father of a little girl mine had met at a mommy and me class. While he had his rough edges, he seemed harmless enough.
He later moved out of the state, and I suspected our relationship would fade away. Then I woke one morning to find he had posted offensive rants that were visible to all my friends.
I fired off a message expressing disappointment and unfriended him. He wrote an obscenity-laced note back and made disparaging remarks about my kid. I thought that was the end of it.
Five months later, he wrote again, saying "I'm thinking about visiting some of my old friends in NJ soon, and I remember where you live!" It wasn't a direct threat, but it was close enough. I went to the police.
The officer took a nuisance report and said he didn't think I'd see this person again (he was right, thankfully), but as we talked he noted that my experience wasn’t unique — and that the department was hearing complaints like mine and being called over disputes that started as Facebook squabbles.
It turns out that harassment is one of the biggest problems Facebook users experience.
A Bristol, Conn. man recently turned himself in on charges ofleaving threatening and sexual messages for a woman he friended on Facebook by using a false name. Bryan Oates allegedly threatened to harm himself and the woman if she would not further their relationship. Police told a local news outlet that Oates had been convicted of a similar incident in 2010.
If there's good news about these sorts of cases, it's that they're often among the easiest types of Facebook troubles to deal with. The site makes it easy to report these kinds of abuse and easier still to block people from contacting you via the site (something I neglected to do, which is how he was able to send me a message).
There's an unfortunate loophole, though, that can make things much worse. Many people (including the woman Oates is accused of threatening) list their cell phone number or home number on their profiles—and Facebook has no control over how people use that.
In Knoxville, Tennessee, a woman whose name was similar to a person suspected of child abuse, received dozens of threatening calls from strangers who found her number via Facebook. (She was not related to the suspect and lives in a different county.)
As frightening as harassment can be, there are much worse things that can happen through the social network. Prostitutes and drug dealers use Facebook as bases of operation – and child molesters have found victims through the site's chat function. (Exactly how often this happens is hard to say. CNBC.com made multiple inquiries to the FBI and Justice Department about the frequency of Facebook-related crimes, but neither agency responded to the inquiries.)
On some levels, the criminal activity is to be expected. With 900 million members, Facebook is bound to attract a percentage of unsavory ones. Realizing this, the site formed a proactive security team years ago to watch out for hackers, pedophiles, and potential identity thieves and weed out objectionable (and illegal) images. It's currently headed by a former federal prosecutor for a U.S. Attorneys' office.
The security group doesn't seek the spotlight, though. A Facebook spokesperson, when asked about how the site handles potential criminal activity, referred me to the site's Safety Center pages.
No matter how thorough Facebook's screening is, some things slip through. And some of them are bad.
In February, Danish citizen Kai Lundstroem Pedersen, 61, was sentenced to 30 years in prison for producing and transporting child pornography and for extortion against an 11-year-old Missouri girl. He met his victims by creating a fake Facebook account where he posed as a juvenile male, convincing them to do sexually explicit acts in a video Web chat, which he recorded and distributed.
Earlier this month, the Justice Department secured a four-year sentence for a California man – James Dale Brown—for attempting to extort sexually graphic images from a 14-year-old.
Meanwhile, as Craig's List has cracked down on prostitutes advertising their services, tech-savvy hookers have turned to Facebook to attract johns.
Sudhir Venkatesh, a professor of sociology at Columbia University in New York, spent 12 months studying how prostitutes are finding clients these days, following 290 women and asking them about past and present practices.
"Even before the crackdown on the [Craig's List] adult-services section, sex workers were turning to Facebook," he wrote in early 2011. "83 percent have a Facebook page, and I estimate that by the end of 2011, Facebook will be the leading online recruitment space."
Generally, Facebook troubles are more personal, though – like what I went through. Last year, for example, two preteen girls hacked into a classmate's Facebook page, posting sexually explicit photos on her wall after they had a fight. They had gotten access to her account when she logged into Facebook at one of the other girl's houses earlier in the day.
A 2011 study by the Pew Research Center found that Facebook users are more trusting of other people than non-users.
"A Facebook user who uses the site multiple times per day is 43 percent more likely than other internet users and more than three times as likely as non-internet users to feel that most people can be trusted," it found.
(A new AP-CNBC poll released Tuesday, however, found that Facebook users cast a wary and suspicious eye on the platform itself: 59 percent of respondents said that they had little to no trust in Facebook to keep their information private.)
Too much trust of others may open the door for scammers and viruses. In January, security company ZoneAlarm issued a report finding that 20 percent of news link feeds open viruses – and four million Facebook users are exposed to spam per day.
Social networking can be fun—and a great way to stay in touch with friends. But just like anywhere else on the Internet, it pays to be on your guard.