St. Louis ? A former American Red Cross worker is accused of stealing identities of three people from a blood donor database. And because she had access to Social Security numbers of more than 1 million people, authorities are concerned there may be other victims.

Lonnetta Shanell Medcalf, 20, of St. Louis, is facing three federal counts of aggravated identity theft and one count of credit card fraud, U.S. Atty. Catherine Hanaway said Friday. Medcalf was indicted by a federal grand jury last month.

Medcalf worked for about five months as a telephone worker at the Red Cross’ St. Louis office. Her job was to call former donors and urge them to give blood again. The office serves as regional headquarters for blood services in most of Missouri, along with southern Illinois and eight counties in Kansas.

As part of her job, Medcalf had access to Social Security numbers of past donors. Hanaway said Medcalf used that information to open credit card accounts with the names of at least three victims, obtaining more than $1,000 in cash and merchandise.

Medcalf was fired March 2, as soon as police in the St. Louis County town of Ladue traced one of the thefts to the Red Cross database, Red Cross spokesman Jim Williams said.

The Red Cross initially thought Medcalf’s database access was limited to about 8,000 people, mostly in the St. Louis and Cape Girardeau areas. Letters were sent to those people in March, informing them of the security breach.

But earlier this month, the Red Cross learned Medcalf had access to names and Social Security numbers for all 1 million people in the three states who are past donors.

The blood supply was never compromised and steps have been taken to ensure against future identity theft, Williams said. The organization no longer requires Social Security numbers from donors, and past donors can ask that their numbers be removed. Also, internal security measures now require security clearance for employees accessing donor databases.

“I just want the general public to know your safety and identity is sacred to us,” Williams said.

Since the Red Cross initially sent out the 8,000 letters, many people have come forward raising concerns about identity theft, Hanaway said. Those cases are under investigation.

“We suspect the number of victims will increase,” Hanaway said.

The Red Cross has begun a publicity campaign and is taking out national ads urging anyone who may have been victimized to come forward. Williams said the national Red Cross database was not accessed by Medcalf, but the organization is publicizing the case nationally in case any past donors from Missouri, Illinois and Kansas have moved away.

A toll-free number for potential victims, 1-866-908-7747, will be operational through June 30. Identity theft complaints also can be filed through the Federal Trade Commission at www.consumer.gov/idtheft.