(Reuters) — A Georgia couple who settled with General Motors Co. last year over their daughter's fatal car crash linked to a faulty ignition switch has filed a new lawsuit against the automaker.

In a complaint filed in state court in Marietta, Georgia, on Monday, Ken and Beth Melton accused GM of fraudulently concealing critical evidence and allowing a company representative to lie under oath.

They claimed that a lead design engineer for Cobalt ignition switches repeatedly testified that he did not know of any design change to the switches, and that GM affirmed those statements.

The company's recent disclosures to the National Highway Traffic Safety Administration and Congress have revealed those assertions to be false, the Meltons' lawyers said in a statement announcing the lawsuit on Monday.

“The Meltons would not have settled their case if they had known of the perjury and concealment of critical evidence,” said the couple's attorney, Lance Cooper.

GM is facing dozens of lawsuits over the faulty ignition switch that has led to the recall of about 2.6 million vehicles.

The defective switch is prone to being jostled into accessory mode while the cars are moving, shutting off engines and disabling power steering, power brakes and airbags. The problem has been linked to at least 13 deaths.

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A GM spokesman said in an emailed statement that the company “denies the assertion that GM fraudulently concealed relevant and critical facts in connection with the Melton matter.”

The company denied it engaged in any improper behavior in that lawsuit, he added.

Brooke Melton, 29, died in March 2010 after the ignition switch on her 2005 Cobalt slipped into accessory mode and she collided with another vehicle.

Ms. Melton's parents settled their original legal claims against GM in September 2013.

On April 11, after GM issued its recall, the Meltons asked the company to rescind their settlement, but it refused.

At least two other families who reached out-of-court settlements with GM over fatal crashes have said they are considering trying to overturn the agreements, after the company disclosed that it had known about the issue for years.

To undo a settlement, plaintiffs would have to convince a judge that they were intentionally misled or defrauded by the other party, according to legal experts.