Lawyers in a Georgia lawsuit against General Motors Co. said at a news conference Monday that they have obtained documents contradicting Anton Valukas’ report and showing that GM was engaged in a “strong case of fraud” and a cover-up of its fatal ignition-switch problems.

The lawyers also said the role of former General Counsel Michael Millikin in the alleged cover-up is still being examined and will be subject to “further inquiry.” Millikin retired under pressure and was replaced by Craig Glidden on March 1. GM spokesman Jim Cain declined to comment on the allegations.