Pinned inside an overturned Ford Explorer on Interstate 5 in Bakersfield, Gabriel Koloszar looked up to see her friend Paulo Aguilar hanging unconscious from his seat belt, his blood dripping down on her.

Rescuers pulled Koloszar out through the windshield. When she tried to stand, another passenger cried out: "Oh my God, Gabby. Your feet!" Only then, she recalled, did she look down to see her mangled flesh.

The trauma of that morning turned to outrage after Koloszar and Aguilar sued U-Haul International Inc., alleging that the accident was caused by a defective tire on the trailer they had been towing.

When their attorneys sought to inspect the tire and rim, they were told that would be impossible.

The evidence had disappeared.

A Kern County Superior Court judge declared in December that he would sanction U-Haul for "extreme negligence" in losing the evidence. Two weeks later, a federal judge in Ohio penalized U-Haul for similar conduct in a separate case.

U-Haul, the leader of the do-it-yourself moving industry, has repeatedly lost, altered or discarded truck and trailer parts sought by injured customers who sued the company, a Times investigation found.

In some cases, the company scrapped or repaired damaged parts in defiance of court orders that they be preserved as evidence.

At least twice, judges have imposed on U-Haul an exceedingly rare and severe sanction for misconduct in a civil case: throwing out the company’s defense and entering judgments in favor of plaintiffs who needed the missing evidence to pursue their claims.

U-Haul said that the few instances of lost or spoiled evidence were purely accidental and that "the complexity of managing equipment across thousands of locations" sometimes led to mistakes.

Although it is not uncommon for parties in litigation to be accused of destroying or discarding documents, legal experts said it is unusual for it to happen with physical evidence.

It is unknown how many times this has occurred in lawsuits against U-Haul. No independent source gathers information on such cases.

U-Haul said judges had sanctioned it for spoiling evidence in "at best, a handful of cases" and had never ruled that it had done so intentionally.

The Los Angels Times identified 11 instances since 1989 in which records show that U-Haul lost, altered or discarded evidence. Judges sanctioned the company in some of those cases. In the others, plaintiffs did not seek sanctions, or the cases were settled before courts could rule on motions for sanctions.

U-Haul said that it has been sued more than 10,000 times over the last 20 years and that the few examples of sanctions should be viewed in that context.

Companies have a duty to preserve evidence not only when a suit has been filed, but also when they know one is likely due to injuries or deaths. Even the inadvertent loss or destruction of evidence may be punished by the courts because it can deprive the other side of a chance to prove its case.

U-Haul said it has strengthened its evidence protection in recent years by requiring its agents to obtain the legal department’s approval before putting equipment from accidents back in service. The company declined to provide a copy of the policy.

Dale A. Oesterle, a business law professor at Ohio State University, said an occasional failure to preserve evidence "may not be an indictment of corporate policy or corporate attitude…. I don’t think you can expect a corporation to have a perfect record."