The National Highway Traffic Safety Administration is coming under increasing fire for its failures relating to the Toyota unintended acceleration debacle. Now, Reuters is reporting that at least two former NHTSA regulators now work at Toyota. What’s more, these individuals may have helped bring to an end four separate NHTSA investigations into Toyota vehicles and unintended acceleration.

According to Reuters, Christopher Tinto, vice president of regulatory affairs in Toyota’s Washington office, joined the automaker in 1994, right after leaving the NHTSA. Christopher Santucci – who now works for Tinto – did the same in 2003.

From 2003 to 2009 the NHTSA opened eight investigations of sudden acceleration involving Toyotas. Of those, three resulted in floor mat recalls and five were closed. Tinto and Santucci worked with NHTSA on Toyota’s responses to the consumer complaints, according to court papers and other documents reviewed by Reuters.

As of January 2010, Toyota has recalled more than 5 million vehicles in the U.S. for problems with sudden acceleration. The recalls started in September, when Toyota announced it was recalling and replacing floor mats on approximately 4.2 million vehicles which were allegedly causing accelerator pedals in the vehicles to become stuck in the depressed position, leading to uncontrollable and rapid acceleration of the vehicle. On January 21, Toyota recalled 2.3 million vehicles due to accelerator pedals on those vehicles becoming stuck in a depressed position, causing unexpected and unsafe acceleration. Toyota accelerator-related problems have been linked to crashes that killed at least 19 people.

Crashes involving Toyota or Lexus vehicles and sudden acceleration have allegedly resulted in 19 deaths between 2004 and 2009.

According to Reuters, the relationship between Tinto and Santucci and the NHTSA is unique. Spokesmen for General Motors Co., Ford Motor Co., Chrysler Group LLC and Honda Motor Co. all told Reuters that they have no ex-NHTSA people who deal with the agency on defects.