Hackers broke into a University of Texas database and stole the names, Social Security numbers and e-mail addresses of more than 55,000 students, former students and employees, officials said.
It wasn't clear whether the information was used to illegally obtain credit cards or withdraw money from bank accounts. School officials said they were notifying the victims.
Travis County prosecutor Ronnie Earle said search warrants related to the case were served late Wednesday in Austin and Houston. He declined further comment. Federal authorities did not immediately return calls.
The theft was discovered Sunday when employees found a computer malfunction, according to Daniel A. Updegrove, the university's vice president for information technology, who described the incident on the school's Web site.
The database was hacked into from a computer in Austin several times beginning on Feb. 26 and ending Sunday. Updegrove said the hackers used a program to query the database with 3 million potential Social Security numbers, resulting in about 55,200 successful matches.
Updegrove acknowledged that the breach could have been prevented with basic precautions.
"We flat out messed up on this one," he said. "Shame on us for leaving the door open, and shame on them for exploiting it. Our number one goal is to get those data back before they get misused."
Forrest Wilder, a senior anthropology major, criticized the university for requiring Social Security numbers for virtually every type of transaction.
"If you check out a library book, it all goes back to a Social Security number," he said. "This is what happens when you promiscuously use a single number as an identity in the community."