He soon changed his focus. Information from the black box in Ms. Melton's Cobalt indicated that power had been cut not only to the power steering, but also to the rest of Ms. Melton's car, Ms. Lundrigan said. Meanwhile, Mr. Cooper also became aware of bulletins GM sent to dealers in 2005 and 2006 pointing out scenarios in which drivers could inadvertently turn off the ignition in various GM models.
In a revised complaint filed in March 2013, Mr. Cooper alleged that as Ms. Melton drove her Cobalt on Georgia's Highway 9, her key moved out of the run position, shutting off the engine and causing her to lose control and strike an oncoming car.
“The impact caused Brooke's vehicle to travel off the highway and into a creek,” leading to injuries that resulted in her death, according to the complaint. GM was accused in the complaint of negligence in designing, testing and manufacturing such a car and of failing to adequately warn consumers.
In total, the firm deposed some 30 people familiar with the ignition-switch issue, including about 12 GM engineers, Ms. Lundrigan said.
Mr. Cooper's “focus on getting really into the internal workings of that corporation, getting into their engineering drawings, communications” helped pressure GM, said Dennis Cathey, a Georgia lawyer who has known Mr. Cooper for more than a decade and worked with him on automotive defect cases. “He has an innate sense of knowing that something could be wrong, and seeks to find out his proof to establish that wrong.”
Even so, Mr. Cooper hadn't received all that he sought from GM. In September 2012, he had asked GM for information on the ignition switches—including related lawsuits and documents on a replacement part described in the dealer bulletins.
The following January, GM provided “a lot more documents,” Mr. Cooper said. They provided even more, he said, after the judge issued an order in February 2013 overruling “GM's general and unspecified objections” to several of Mr. Cooper's discovery requests and requiring the carmaker to produce “all responsive documents and materials” by the end of the month.
In subsequent depositions, though, GM engineers referred to documents that the auto maker hadn't provided, Mr. Cooper said. In June, he filed a motion seeking penalties against the car maker for withholding information.
In September, two months ahead of the suit's trial date, GM and the Meltons reached a confidential settlement, Mr. Cooper said. GM hadn't provided the additional documents, he added.
A related suit could still reach trial.
Mr. Cooper also sued Thornton Chevrolet, the dealership in Lithia Springs, Ga., where Ms. Melton brought her car for repair just days before her fatal accident, according to the lawsuit. On the visit, the suit alleges, Ms. Melton raised concerns about the engine shutting off during driving. Thornton failed to identify and implement the GM bulletin to dealers aimed at addressing the problem, Mr. Cooper said. While the judge in the case has ruled on pretrial issues, a trial date hasn't been set, according to Ms. Lundrigan.
The dealership's attorney, Matthew Stone of Freeman Mathis & Gary L.L.P., said the firm couldn't comment on pending litigation.
GM's recall, and word of Mr. Cooper's knowledge in the case, has given the solo lawyer a sudden popularity. The firm has received more than 70 calls in the past few weeks—from would-be plaintiffs, attorneys seeking to partner with Mr. Cooper and people thanking him for publicizing the issue—said Victoria Schneider, the firm's marketing director.
“I've talked to a few lawyers,” Mr. Cooper said.
Mr. Cooper is bound by a protective order in the Melton case, in effect since December 2011, that bars him from sharing material and deposition testimony GM has designated confidential. He must also return GM's documents after the case is finished. Copies of depositions in the case reviewed by Bloomberg News are heavily redacted, with the majority of some testimony blacked out.
While Mr. Cooper hasn't filed more lawsuits since GM's recall announcements in February, his firm's investigation of the situation is continuing, he said.
“If we were to file another lawsuit against GM, we'd call GM's lawyers up and we'd say, ‘Hey, we've got all these documents, let us use them in the new case.' If they say no, we'd file a motion with the judge,” he said. “We've had these situations before where most of the time, the manufacturer will be reasonable and allow you to use them.”
Mr. Cooper said the process has been gratifying for Ms. Melton's family. “They hope the public will now know the whole truth about what GM did,” he said.
This Bloomberg News report appeared on the website of Automotive News, a Detroit-based sister publication of Tire Business.