Investigative authorities have questioned Takashi Usami, former chairman of Mitsubishi Fuso Truck & Bus Corp., over an alleged false report issued in connection with a fatal accident caused by a defective vehicle in 2002, informed sources said Sunday.

Usami, 63, resigned as chairman of the firm in mid-April to take the blame for the company’s long delay in recalling Mitsubishi Fuso large trucks and buses featuring defective wheel hubs.

Investigators grilled Usami as part of efforts to establish a case against him and other executives suspected of issuing a false report on the fatal accident in violation of the road traffic law, the sources said.

The accident in question occurred Jan. 10, 2002, in Yokohama. A 29-year-old woman was killed after she was hit by a wheel that came off a truck made by Mitsubishi Motors Corp. Her two children were injured.

At the time of the accident, Mitsubishi Fuso was part of Mitsubishi Motors. It was spun off in January 2003.

Mitsubishi Motors reported the accident to the Land, Infrastructure and Transport Ministry in early February 2002 — less than a month after the accident.

In its report, Mitsubishi Motors concluded that the accident had been caused by poor maintenance and overloading on the part of the user, causing the wheel hubs to become worn.

But the carmaker had not launched an internal investigation — including conducting strength tests on hubs — at the time it submitted the report, leading investigative authorities to suspect that Mitsubishi Motors tried to avoid recalls.

The ministry decided that a recall was unnecessary after seeing the report.

Mitsubishi Motors conducted its own wheel-hub investigation after it submitted the report to the ministry. In May 2002, it obtained data showing that about 30 percent of hubs develop cracks regardless of the degree of wear.

Mitsubishi Fuso reported the new data to the ministry last March. It also decided to recall trucks and buses — more than two years after the fatal accident in Yokohama and 12 years after the first accident was reported, in 1992.

When Mitsubishi Motors submitted the initial report in February 2002, Usami was vice president of Mitsubishi Motors in charge of its truck and bus operations.