DETROIT -

The storm swirling around General Motors continues to get worse. Local 4 has learned new information about the design defect at the heart of the recall that's under serious scrutiny from the feds.

It's a faulty ignition switch that's launched the recall of 1.6 million GM vehicles and is tied to 12 deaths and 31 accidents -- numbers that could potentially rise.

So what was so faulty? A spring-loaded plunger inside the ignition. The part was 10.6 millimeters and could cause the key to switch out of run and disable the safety system.

In 2007 GM changed that spring-loaded plunger to 12.2 millimeters, effectively taking care of the problem, but told no one. In video depositions obtained by NBC News, not even the design engineer of the ignition in the Cobalt one for the affected vehicles knows who authorized the change.

GM has more to worry about than consumer perceptions right now. There are strict laws that govern automakers when it comes to defects. If a problem is discovered, the company has five days to report it to the government or face fines that could total $35 million.

GM, now under new CEO Mary Barra's leadership, isn't denying mistakes were made. Barra has apologized, but will the old GM bring down everything the new GM has been working toward?

"Something went wrong with our process in this instance and terrible things happened," Barra said.