An engineer responsible for designing ignition switches at General Motors, or GM, (NYSE:GM), told lawmakers that he had forgotten his decision to order an upgrade to malfunctioning switches that have been linked to at least a dozen deaths and triggered a record number of vehicle recalls by the Detroit automaker, the New York Times reported Wednesday.

Raymond DeGiorgio, who has been with GM since 1991 and was suspended last month, had reportedly approved changes to the ignition switches in 2006 and authorized component maker Delphi to upgrade them at its manufacturing plant in Mexico. However, he denied the claims during a deposition last April, the Times reported, and said that the changes were made without his knowledge and authorization.

However, on May 19, during a round of questioning that lasted for nearly 10 hours, DeGiorgio claimed he had forgotten about authorizing the upgrade because it was a decision taken seven years ago and was part of a set of different changes made at the time, the Times reported. During the interrogation, DeGiorgio also did not indicate that CEO Mary Barra knew anything about the faulty ignition switches, the report said, citing people familiar with the session, and added that DeGiorgio was “genuinely upset” with the deaths linked to the malfunctioning component.

“He (DeGiorgio) came across as if he was just overburdened and just missed it,” an official told the Times, adding: “He definitely said he was more focused on electrical problems.”

The embattled car company has so far recalled a total of 2.6 million vehicles produced between 2003 and 2010, and was fined $35 million in May by U.S. transportation officials for not reacting promptly to the defective switch problem. The total number of accidents linked to the faulty switches now stands at 47, according to company estimates. And, according to the Times, GM has connected the switch defect to 13 deaths and this number is expected to rise according to federal regulators.

The defective ignition switches, found in a number of models including Chevrolet Cobalts and Saturn Ions had caused the engines to shut down suddenly and disable the power steering, power brakes and airbags in the vehicles. And, the investigations against GM, which began in 2004, have also tried to understand why the automaker did not recall the vehicles when they discovered the problem and whether it downplayed the extent of the problem.