A memo written by a Big Dig safety officer warning superiors at his construction company that parts of a tunnel ceiling could collapse appears to be a fake, the company said Wednesday.

The memo is dated May 17, 1999, and bears the signature of John J. Keaveney. It raised several concerns about the safety of the bolt-and-epoxy ceiling design in the Interstate 90 connector tunnel where a woman was killed July 10 when ceiling panels fell on her car.

The bolt-and-epoxy system has been the focus of the investigation into the collapse in the $14.6 billion highway project.

The memo was mailed to The Boston Globe late last month without Keaveney's knowledge, but he later verified to the newspaper that he wrote it while working for Modern Continental Construction Co. Click here to read the last story about Keaveney's memo.

The company issued a statement late Wednesday that said it has conducted a thorough review of its files and found no evidence of Keaveney's memo. Some documents also appear to contradict the memo's timing, the company said.

"Based on an extensive review of documents, including invoices for delivery of materials, commencement-of-work records, and safety reports signed by Mr. Keaveney, Modern Continental believes the memo he allegedly prepared in May 1999 was fabricated," the statement said.

Keaveney's lawyer said his client maintains the authenticity of the memo, although he acknowledged that Keaveney may have made some mistakes about the exact timing of some events.

"When provided a copy of the memo by a reporter on July 25, John Keaveney verified it as his own without hesitation, and he stands by that memo," attorney Edward G. Boyle III told the Globe on Wednesday.

Neither Boyle nor Keaveney immediately returned calls from The Associated Press on Wednesday night. Keaveney no longer works for Modern Continental.

The memo warns that someone could "be seriously injured or even worse killed as a result" of the ceiling design. It also questions "how this structure can withhold the test of time."