How do you hide in the digital age?

Cynthia doesn't want to be found.

More than 10 years ago, she was nearly beaten to death by her ex-husband and, years later, an intruder came into her house and raped her.

Cynthia, who did not want her real name published for safety reasons, began to rebuild her life with the purchase of a house in the East Bay. Fearing her ex-husband or her attacker may find her, she keeps her address confidential through California's Safe at Home program.

But type her real name in one of the several online services that specialize in people searches and you'll find her address.

"I don't ever want this individual or my ex-husband to ever know where I am, but all (they have) to do is type my name and there I am, home address and everything," she said. "What good is it for me to be in the Safe at Home program if my information is out there anyway?"

Web sites that specialize in finding people have been around for more than a decade, but the rise of social networks and the growing availability of public information on the Internet have enhanced their ability to compile rich portraits of people's lives.

But the trend has not escaped the attention of privacy advocates, who say the lack of regulation in the field has left the door open to inaccuracies, allowed companies too much control over individuals' information and put people's reputations and physical safety on the line.

Searching for data

Services like Spokeo, Pipl, Wink, Jigsaw and Microsoft's EntityCube work in similar ways, but they differ from each other by the sources they tap, the way they package information or by focusing on specific topics like professional information, social network searches or people's "dateability."

Analysts said the online people search industry is a strong and financially sound sector with high demand. Type the words "find" and "information" in Google, for example, and six of the top 10 suggestions have to do with finding people online.

"The reality of the Internet is nothing more than creating closer connections between people. It stands to logic that the most searched thing on the Internet, the topic (people) want to know about the most, is other people or themselves," said Nick Matzorkis, an Internet entrepreneur who created and sold US Search and ZabaSearch, two pioneering and controversial people search engines that offer free limited information and sell background checks and detailed reports.

Matzorkis' businesses were built on the premise that people have a strong urge to connect - a lesson he learned at age 9 when his father sold his house, quit his job and moved his family to the Greek island of Crete to find his distant relatives.

Indeed, beyond the more common searches for old flames, former classmates and prospective dates, these services also have reunited separated relatives.

But consumer and privacy advocacy groups and federal regulators receive a regular flow of angry complaints about the accuracy, incompleteness or simple presence of personal information on these sites.

World Privacy Forum executive director Pam Dixon said the existence of accessible and abundant information on individuals has created new risks to people's personal safety while giving users little control over their information. Privacy advocates also worry about the negative repercussions of people making judgments about others - like an employer considering job applicants - based on the sometimes incorrect or partial information found on these services.

Addresses and maps

And then there are the online services that do not specialize in people searches but nonetheless are putting vast amounts of information about individuals on the Internet. Last month, for example, Cynthia found out that a simple Google search for her name returned a link to BlockShopper.com that contained her full address and a Google Maps image of her home.

BlockShopper President Brian Timpone said his real estate news and research service - which provides real estate content for The Chronicle - collects only public records, unlike information brokers that create profiles with additional purchased data. He said his Web site provides a public service by putting real estate and tax records into context and helping investigators track fraud schemes.

Matzorkis said there is nothing wrong with using records that had been public long before the Internet.

These services receive their share of complaints from users who want information about them removed, but companies like ZabaSearch and Pipl say they do not keep information on people - they just dig the Web for any given name and direct people to where the information is.

"We can't take down data," said Jonathan Schreiber, an executive at Pipl, a Web site that specializes in searching for online content beyond the most popular search results.

"If there's data out there on a Web site, there's nothing we can do about it," Schreiber said. "We tell (users) where the information is coming from and help them understand what the exposure is to the extent we can."

New concerns

But privacy advocates said the increased ease of access brought by the centralization of personal data is a double-edged sword. Obtaining information is more convenient, but it has created a new set of concerns.

Paul Stephens, director of policy and advocacy at Privacy Rights Clearinghouse, said there is a big difference between files in a courthouse or government office that people must physically visit to obtain, and digital records available to millions of users with a few clicks of the mouse.

Physical records "suffer from what we refer to as 'practical obscurity,' " he said. "A nosy neighbor is not likely to go to a government office and get a piece of information about you, and it wouldn't be cost effective for a direct marketer to go down there and get that information."

Some companies said they are working with consumers and privacy groups in an effort to find a balance, and that solutions - like offering option to remove the information or control what is displayed on these sites - are already surfacing.

But critics said that self-regulation won't fully address all the concerns because only a handful of companies are willing to accommodate people worried about their privacy. Dixon said these services need to be regulated in a way similar to how the Fair Credit Reporting Act sets the rules for the collection and distribution of consumer credit data.

In that spirit, Cynthia said she plans to write a letter asking U.S. Attorney General Eric Holder and California legislators to draft guidelines on how these services should handle information that might place victims of violence like her at risk.

"The message will be that homeowners and consumers in general have a right to feel safe in their own homes, and these information brokers are infringing upon that right," she said.

E-mail Alejandro Martínez-Cabrera at amartinez-cabrera@sfchronicle.com.

This article appeared on page D - 1 of the San Francisco Chronicle