Texas attorney Bob Hilliard, who represents plaintiffs suing General Motors (GM), believes as many as 5,000 people died in connection with the automaker’s ignition-switch issue.

According to Hilliard, at least 100 deaths have already been brought to the attention of lawyers involved in GM cases. He said the total number of victims could be closer to 5,000, including passengers in other vehicles involved in a switch-related accident.

Hilliard developed his estimate using the total number of highway deaths since the affected vehicles hit showrooms.

“There’s no way to ever prove that number definitively. It’s my subjective belief,” Hilliard acknowledged, adding that he feels “comfortable” with his figure.

GM spokesman Greg Martin disputed Hilliard’s estimate. The company has said it is aware of 13 fatalities tied to the faulty ignition switches.

“However, the compensation program that will be independently administered by Kenneth Feinberg will determine those who will be compensated as part of the program,” Martin said.

Martin also said GM will disclose the number of people who went through the compensation program once it’s completed.

Feinberg, who handled compensation funds for 9/11 and the BP (BP) oil spill, was retained by GM to develop a compensation plan for accident victims and administer the fund, which will be uncapped. Late last month, Feinberg said the voluntary program will begin accepting claims on Aug. 1. He declined to estimate how many claims will be submitted.

In a letter sent to regulators in March, the Center for Auto Safety said crash data indicate that 303 deaths were a result of the defective ignition switches, which can slip out of the “run” position and cause vehicles to stall.

Last month, Reuters conducted an analysis of government fatal-crash data that suggested at least 74 people died in related accidents.

Hilliard expects the number of claimants as part of Feinberg’s compensation program to be in the hundreds, well below his estimate of 5,000 deaths. He added that the Department of Justice should consider how many deaths are unaccounted for if the agency decides to fine GM for the long delay in recalling Chevrolet Cobalts and other cars.

The attorney will discuss the issue on a special edition of The Willis Report at 5 p.m. Thursday.

Follow Matthew Rocco on Twitter @MatthewRocco