Updated

The authenticity of newly unearthed memos stating that George W. Bush failed to meet standards of the Texas Air National Guard (search) during the Vietnam War was questioned Thursday by the son of the late officer who reportedly wrote the memos.

"I am upset because I think it is a mixture of truth and fiction here," said Gary Killian, son of Lt. Col. Jerry Killia (search)n, who died in 1984.

Another officer who served with Killian and a document expert also said Thursday the documents appear to be forgeries.

Gary Killian, who served in the Guard with his father and retired as a captain in 1991, said one of the memos, signed by his father, appeared legitimate. But he doubted his father would have written another, unsigned memo that said there was pressure to "sugar coat" Bush's performance review.

"It just wouldn't happen," he said. "The only thing that can happen when you keep secret files like that are bad things. ... No officer in his right mind would write a memo like that."

News reports have said the memos, first obtained by CBS's "60 Minutes," were found in Jerry Killian's personal records. Gary Killian said his father wasn't in the habit of bringing his work home with him, and that the documents didn't come from the family.

The personnel chief in Killian's unit at the time also said he believes the documents are fake.

"They looked to me like forgeries," Rufus Martin said. "I don't think Killian would do that, and I knew him for 17 years."

CBS stood by its reporting. "As is standard practice at CBS News, the documents in the '60 Minutes' report were thoroughly examined and their authenticity vouched for by independent experts," CBS News said in a statement. "As importantly, '60 Minutes' also interviewed close associates of Colonel Jerry Killian. They confirm that the documents reflect his opinions and actions at the time."

Independent document examiner Sandra Ramsey Lines (search) said the memos looked like they had been produced on a computer using Microsoft Word software, which wasn't available when the documents were supposedly written in 1972 and 1973.

Lines, a document expert and fellow of the American Academy of Forensic Sciences (search), pointed to a superscript — a smaller, raised "th" in "111th Fighter Interceptor Squadron" — as evidence indicating forgery.

Microsoft Word automatically inserts superscripts in the same style as the two on the memos obtained by CBS, she said.

"I'm virtually certain these were computer-generated," Lines said after reviewing copies of the documents at her office in Paradise Valley, Ariz. She produced a nearly identical document using her computer's Microsoft Word software.

The White House distributed the four memos after obtaining them from CBS News. The White House did not question their accuracy.