Anyone who drives the nation's highways will see them -- pieces of tire tread sitting along side the road. Often just discarded and left there as trash after an accident, they could be important evidence in cases involving possible tire failure.

Cooper Tires, the nation's fourth largest tire manufacturer, hired an investigator who would go pick up that tread in accidents involving Cooper Tires.

That individual, Frank Ruggier, testified in a deposition in May 2005 in Phoenix that he would search the Internet every day, looking for reports of crashes involving tires throughout the United States.

"I look, usually, at the metro section of the newspaper," Ruggier testified. "Looking for key words, such as accident, fatal, death."

In a case involving an Arizona accident that left one woman dead, Ruggier testified that Cooper Tires paid him $75 an hour to go to accident sites. He would take pictures and collect evidence. If he found pieces of tread he took it -- and gave it to Cooper Tires. This was sometimes days or weeks after an accident, and after police had finished their on-scene investigation.

Ruggier would deliver any evidence he found to Cooper headquarters in Findlay, Ohio. Ruggier testified that local authorities in Arizona had directed him to the accident site -- but that he never told anyone he had removed the tread.

Ruggier was asked during the deposition: "At no time did you tell Arizona authorities that you had recovered anything that could conceivably be physical evidence at the scene, is that right, sir?"

"That is correct," answered Ruggier.

Company Keeping Quiet?

Tire companies routinely use investigators. Ruggier also did occasional work for Bridgestone-Firestone, Dunlop, Continental General. Dunlop and Bridgestone-Firestone told ABC News that Ruggier never delivered pieces of tread to them. The other companies only confirmed Ruggier had been employed by them from time to time.

Florida attorney Bruce Kaster is suing Cooper Tires in the death of Timica Bradley. She and her husband, both in the Navy, and their young son were traveling from California to their new posting on the East Coast when the tread on their Cooper tire separated.

While in New Mexico, Timica Bradley was driving and lost control of the vehicle, and the vehicle rolled. Bradley's husband Johnny was severely injured in the crash, and their then-7-year-old son survived with minor injuries. Johnny Bradley's lawsuit alleges the tires were defective; Cooper says the accident was not the fault of the tires and had sent someone to the site to collect the treads.

Kaster told ABC News, "We didn't know that Cooper had sent someone to the scene and removed the physical evidence. Cooper knew it, but we didn't."

"Why would they even try to, you know, be … sneaky with it?" Bradley said.

Cooper Tires officials say Ruggier removed the tread some 11 days after the accident, after police had cleared the scene. The company told ABC News its aim is to "gather and preserve evidence so that the truth can be told."

"All we want to do is to gather evidence to defend our products," said a Cooper spokesperson.

But in January, a Cooper executive was asked in a deposition involving the Arizona case who, other than company officials, was told about the evidence. Cooper Vice President and Treasurer Stephen Schroeder answered, "I don't know that anybody else is notified."

He was then asked, "Including the attorneys for the plaintiff?"

Schroeder said, "I have no direct knowledge of anyone else."

Attorneys suing Cooper allege the company keeps quiet about the treads to stymie lawsuits.

Cooper Tires calls that "spin … provided by plaintiff's lawyers and others with a financial interest against Cooper Tires."

In the Bradley case, Cooper did try to discourage Bradley's lawsuit in a letter to his attorney, saying "it would be difficult … to prove any claims" because of lack of evidence.

It wasn't until five months later that Cooper revealed it had the tread, as part of the court discovery process.

Experts Say Cooper Not Breaking the Law

In the Arizona case, Elisa Loza died when she was ejected from a van that rolled over after the tread on a Cooper tire separated. Loza was not wearing a seat belt.

Ruggier testified in a deposition in the case that he went to the scene and collected pieces of tread. But Cooper Tires says it has no record of that, cannot locate any such tread, and believes that Ruggier did not, in fact, deliver any tread to them in that case.

Kent Hammond, the attorney in the Loza cases, says having tread evidence available would have helped factfinders "to really determine the truth as to what happened."

Legal experts tell ABC News that Cooper is not breaking the law by collecting evidence, such as tire tread, from the scene of an accident. The company is obligated, however, to preserve any evidence it receives and produce it, if asked, during a lawsuit.

Cooper Tires no longer employs Frank Ruggier. They ended the arrangement after learning Ruggier is a convicted felon. The company says it is still using other investigators to go to accident scenes.

Plaintiffs' lawyers say now that they know the company is doing this -- they will be asking: "Where's the tread?"