The Alameda Food Bank has mailed a letter to 8,000 identified and potential donors informing them of an apparent mail theft that has cost the nonprofit organization an unknown amount in contributions and left officials concerned about identity fraud.

The alleged theft occurred between June 11-14 at the postal facility on Shore Line Drive, where the food bank maintains a post office box. Alameda police said the missing mail could have contained several weeks' worth of donations, and food bank officials are urging anyone who mailed a contribution between May 24-June 14 to check with their financial institution for signs of identity theft.

"We are letting them know that if they sent something in, it may be compromised," said Paul Russell, executive director of Alameda Food Bank. So far none of the donors the organization has been able to identify has reported any suspicious activity, Russell said, but overall "we don't know whose mail was taken."

Russell said all donations the organization actually received have been acknowledged with a thank-you note. Anyone who mailed a contribution and did not receive acknowledgment from Alameda Food Bank should consider that mail part of the missing batch, he said.

Donations made through the organization's website were not affected by the theft.

According to Inspector Hillary Rickher of the U.S. Postal Inspection Service, the agency has an "open and ongoing investigation." The food bank, however, said it has received no indication that the missing mail will be located.

"It appears unlikely at this point that the mail, which included donations, will ever be recovered," wrote board President Neil Rubenstein in the letter sent late last week to potential contributors. "We have no indication at this time that any personal information has actually been compromised or used improperly, but are sending this letter because of the possibility that it may happen."

Rubenstein encouraged anyone with concerns that a contribution was not received to contact the food bank. "On behalf of the board of directors, we ask for your understanding and appreciate your continued support," his letter concluded.

There is no evidence that the post office box was forced open, according to Alameda police Sgt. Jill Ottaviano. "The box was not circumvented; it was not damaged in any way. We don't know if it was an inside job or not," she said. The absence of camera footage will make any investigation difficult, Ottaviano added.

Local police are no longer directly involved in the case due to the federal nature of the crime.

For food bank donor and volunteer Tommie Anderson, news of the theft came as a shock.

"I was very surprised because I have given donations a couple of times a year for the last five or six years," she said, "and I have never had an issue."

Anderson's most recent donation is among the missing ones, but she plans to resubmit her contribution.

"It's just a wonderful program and they do so much for so many people," she said.

Alameda Food Bank provides food to an average of 1,350 low-income Alamedans per month. Founded in 1977, the organization is staffed and run largely by volunteers.