Updated

The discovery of missing mental health records of the Virginia Tech gunman has victims' families and the governor questioning the thoroughness of the criminal investigation into the worst mass shooting in modern U.S. history.

The potentially explosive evidence eluded authorities for more than two years until Seung-Hui Cho's files turned up at the home of a former university counseling official, angering families still struggling to understand how the killer fell through the cracks at the university. The development, disclosed in a memo obtained Wednesday by The Associated Press, represents another embarrassing lapse in the case.

"Deception comes to my mind in my first response," said Suzanne Grimes, whose son Kevin Sterne was wounded. "It gives me the impression, 'What else are they hiding?"'

List of Victims in Virginia Tech Massacre

The contents of the file have not been made public, and Gov. Tim Kaine said it is unclear why Dr. Robert C. Miller, former director of the campus clinic where Cho was counseled because of his disturbing behavior, took the records home more than a year before Cho killed 32 people and committed suicide on April 16, 2007.

The governor said he was dismayed that it took so long to find the records.

"That is part of the investigation that I am very interested in and, of course, I'm very concerned about that," Kaine said.

The commission that was appointed by Kaine never interviewed Miller.

Victims' families want to know whether the file contains warning signs that could have prevented the rampage.

Click here to read witness accounts of the grisly shootings

"Would things have been different if we had this information? What information is in those records?" asked Lori Haas, whose daughter Emily was wounded in the shootings.

Miller, 54, declined to comment when reached by telephone at his private practice.

State officials said they would release the records publicly as soon as possible, either by getting consent from Cho's estate or through a subpoena. The medical records are protected under state privacy laws.

Miller told his attorney about Cho's file last Thursday, said Mark E. Rubin, the governor's chief legal counsel. According to a university memo shared with victims' families, Miller took the records for Cho and several other students home around the time he left his job at the center in 2006.

Click here for more information on the gunman

After the massacre, the counseling center conducted an exhaustive search for the records in 2007, and Miller told investigators at the time that he didn't know where they were, university spokesman Mark Owczarski said.

Virginia State Police are investigating whether a criminal act was committed, spokeswoman Corinne Geller said. Kaine said it was illegal to remove records from the center.

The families of two of the dead were already claiming that Miller withheld troubling information about Cho. A lawsuit they filed in April claims Miller was told by Cho's English professors about his disturbing behavior and by the school's residential director that Cho had a history of erratic behavior and suicidal thoughts and had "blades" in his room.

The lawsuit claims Miller never passed that information on to either of the therapists from the counseling center who dealt with Cho during three 45-minute triage sessions in 2005.

Click to read about the hero professor who was killed trying to help students escape

Notes of the warnings to Miller or those made by the therapists concerning the three meetings were never found by investigators. It is unclear if those are part of the recovered records.

"Why would he take any student mental health records to his home at any time, and why that student?" said Robert T. Hall, an attorney for the two families. "It certainly is a question of whether there is more to the Seung-Hui Cho mental health history than we've been told."

The Virginia Tech Review Panel interviewed more than 200 people. The leader of that investigation, former Virginia State Police Superintendent Gerald Massengill, said investigators interviewed Miller's successor at the clinic, but not Miller.

Massengill said Cho's records could be critical to understanding the rampage and "should give us a better understanding of what actions the university did or did not take."