U.S. Sen. Amy Klobuchar is joining the bipartisan call for a criminal investigation into Veterans Affairs officials and staffers who manipulated appointments and wait lists for ailing veterans seeking health care.

Klobuchar has signed on to a letter urging Attorney General Eric Holder to open a criminal investigation. Republican Sen. John McCain of Arizona and Democratic Sen. Richard Blumenthal of Connecticut wrote the letter.

The Justice Department already is involved, but hasn't opened a specific investigation. The VA's Office of the Inspector General has pledged to pass along any evidence of possible criminal activity to the Justice Department for legal assessment, but so far Justice has maintained a consulting role.

“Evidence of secret waiting times, falsification of records, destruction of documents, and other potential criminal wrongdoing has appalled and angered the nation, and imperiled trust and confidence in the Veterans Health Administration,” the lawmakers wrote.

“While we commend and appreciate the IG's pursuit of his inquiry, an effective and prompt criminal investigation must inevitably involve the resources of the Department of Justice, including the FBI.”

Franken sent his own letter to Holder on Wednesday, urging him to "investigate this matter promptly."

A VA internal audit released Monday found that facilities in Minneapolis and Rochester are among 112 nationwide identified for “further review and investigation.”