Story highlights Office of Inspector General confirmsit has staff investigators on the ground in San Antonio

A VA scheduling clerk in San Antonio says he and colleagues were "cooking the books"

They were told to assert that vets had "zero" waits for appointments, he claims

The VA says its "internal fact-finding" determined these claims were "not substantiated"

Clerks scheduling medical appointments for veterans were "cooking the books" at their bosses' behest to hide the fact some had to wait weeks, if not months, for appointments, a VA scheduler in San Antonio said Thursday.

The Office of Inspector General confirms to CNN that it has staff investigators on the ground in San Antonio looking into the allegations.

The allegations surrounding this Texas VA hospital comes as the federal department fends off claims of potentially deadly delays at other facilities, including claims of a secret wait list in Phoenix that was first reported by CNN.

The VA's official policy is that all patients should be able to see a doctor, dentist or some other medical professional within 14 days of their requested/preferred date. Any wait longer than two weeks is supposed to documented.

Yet Brian Turner, a Veterans Affairs scheduling clerk based in San Antonio, said Thursday that some who called to make appointments at his facility did end up waiting longer, yet such delays were never reported.

For example, he said, they might be told the next available appointment wasn't for several months. It would be scheduled for then, but marked in official files as if the patient had put off their appointment until then by choice.

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"What we've been instructed was that -- they are not saying fudged, there is no secret wait list -- but what they've done is come out and just say 'zero out that date,' " Turner said. The "zero," in this case, suggests the patient didn't have to wait at all.

"It could be three months and look like no days (wait)," he added. "It looked like they had scheduled the appointment and got exactly what they wanted."

The Veterans Affairs public affairs office said that Turner's allegation has been looked into, without any finding of wrongdoing.

"Based on our internal fact-finding conducted April 25-28, we found the claims by this employee were not substantiated," the VA statement said. However, the Office of Inspector General says it is conducting its own investigation. Turner tells CNN he has already been interviewed by OIG staff.

The claim comes amid strong public pressure on the U.S. Department of Veterans Affairs and its leader, Eric Shinseki , after CNN reporting unveiled e-mails that allegedly discussed the destruction of a secret list of veterans waiting for care at a Phoenix VA hospital.

Shinseki has ordered a "face-to-face audit" at VA clinics, a department spokesman said on Thursday. Earlier the same day, a House committee voted to subpoena Shinseki in the wake of such accusations that his department is responsible for deadly delays in health care.

Turner told CNN that he's become a witness in an investigation by the VA inspector general's office focusing on delayed care, alleged falsification of records and possible medical harm to veterans at the San Antonio facility. Turner, a former Army soldier himself who still works at the VA, said he has asked to be protected under federal whistle-blower laws.

As to the VA's earlier fact-finding efforts, Turner said that no one asked him about his allegations. In fact, he said, when he began expressing his concerns to other staff members, he was called in and told not to e-mail another person.

"They shut me up the very next day," Turner said.