It was not clear Thursday how much overlap might exist between the 4,000 documents cited in the 2012 letter and the 4,000 referred to in Ferriero’s memo.

No one from the center, off Interstate 270 in the Spanish Lake area, or the National Archives has responded to questions about the full extent of the record loss since the Post-Dispatch first reported in late January that more than 1,800 records had been affected.

The records were not entire files, but individual documents that were supposed to be filed in “existing service folders that had been retired ... years ago,” Ferriero wrote. Many were computer-generated notifications of the deaths of long-retired veterans.

The center holds about 100 million records dating to the 1800s, more than half of them of veterans.

No veterans have been denied benefits, Ferriero wrote, and some records can be reconstructed. But 132 people were notified that their “personal data was breached,” the memo says, and were offered credit monitoring services.

U.S. Attorney Richard Callahan said this month that an audit found only one veteran who had been affected, and that document was re-created.