LOS ANGELES » The first lady and the Vice President are among the latest public figures to have their private information posted on a mysterious website, and the Secret Service has joined the investigation into the postings that include documents from people ranging from rapper Jay-Z to the head of the FBI.

The site includes Social Security numbers, credit reports, addresses and phone numbers.

It bears an Internet suffix originally assigned to the Soviet Union, and many of the pages feature unflattering pictures or taunting messages of the person featured. Others whose information is posted include pop star Britney Spears, Attorney General Eric Holder, former Alaska governor Sarah Palin and former California governor Arnold Schwarzenegger.

Both the FBI and the Secret Service said Tuesday they were investigating the site.

White House Press Secretary Jay Carney said he had “no assessments to offer” on the situation and referred questions to the Secret Service, which wouldn’t provide further details.

The site grew from 11 names to 18 in the first 24 hours since it became public, with its operator adding additional features to count the number of visitors and a link to a Twitter account. It offers no explanation about why the targets were selected or how the information was obtained. The Twitter account includes an anti-police message in Russian.

Social Security numbers posted on Jay-Z, Mel Gibson and others matched records in public databases. Social Security numbers are not public records, although they used to be included in some court filings. Many courts require the information be redacted from filings since the numbers can be used to steal a person’s identity and open credit accounts in their name.

Los Angeles police also are investigating, trying to determine how information was obtained, including the address and credit report of Police Chief Charlie Beck.

Cmdr. Andrew Smith said confidential information on top police officials has been posted online at least twice before.

“People get mad at us, go on the Internet and try to find information about us, and post it all on one site,” Smith said.

“The best word I can use to describe it is creepy,” he said about the practice. “It’s a creepy thing to do.”

Frank Preciado, assistant officer in charge at the LAPD online section, said the postings are illegal. He said the information on the police chief was likely taken from what is supposed to be a secure database of city employees.

The site’s page on Beck includes a reference to former officer Christopher Dorner, who apparently committed suicide after he killed four people during a multi-day rampage. Beck’s page included the message “YouCantCornerTheDorner” and an image of a woman protesting police corruption.

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Associated Press Writer Tami Abdollah in Los Angeles and White House Correspondent Julie Pace and writer Pete Yost in Washington contributed to this report.