Massachusetts senator says highway safety agency "fell down" in GM investigation

Laura Christian's 16-year-old daughter, Amber, died inside a Chevy Cobalt, on July 29, 2005.

"I went downstairs and my phone rang," Christian recalled. "Amber had been in an accident and she didn't make it."

It is the first death linked to the General Motors faulty ignition recall, involving one and a half million GM cars.

Now the federal government is investigating whether GM dragged its feet on the recall. But there are also concerns that the government was slow to respond as well.

GM was made aware of this. So was the National Highway Traffic Safety Administration, or NHTSA, the agency charged with improving auto safety.

No recall was issued, and the news never reached the public, because Amber's adoptive parents reached a settlement and signed a confidentiality agreement with GM.

Complete Coverage: General Motors Recall

Christian, Amber's biological mother whom she reunited with exactly one year before the accident, was not part of an agreement with GM.

"I think that it's a good agency that, here, just fell down on the job," Markey said.

On Thursday, NHTSA told CBS News that they constantly monitor accidents.

"The data available... at the time did not contain sufficient evidence of a possible safety defect trend that would warrant the agency opening a formal investigation," it said.

Asked who was to blame, Markey said, "I think that obviously GM withheld critical information but NHTSA could have been more aggressive and they should have been more aggressive."

What does Christian think is the message to GM?

General Motors declined an on-camera interview but said, "Ensuring our customers' safety is our first order of business. We are deeply sorry and we are working to address this issue as quickly as we can."

GM said it was working with NHTSA on the latest investigation.