In Her Head: How Did Nowak Snap?

How does an intelligent, successful, seemingly well-adjusted woman snap?

It's the question many are asking after astronaut Lisa Marie Nowak was charged with attempted murder in what police are calling a love triangle.

Nowak graduated from the U.S. Naval Academy with a master's degree in aeronautical engineering. She has a teenage son and two twin girls. Yet, she drove over 900 miles wearing diapers, donned a disguise and, with a BB gun and pepper spray, confronted Air Force Captain Colleen Shipman, a woman she believed was a competitor for the affections of fellow astronaut William Oefelein.

On "Good Morning America," psychoanalyst Bethany Marshall shed light on what might be going on in Nowak's head. She said mental illness might have driven Nowak to self-destruction.

"There's a certain category of people who fall into a category of a kind latent mental illness, which is called having a 'psychotic core.' It can be covered by having an articulate, accomplished personality," Marshall said. "But one stressful event can shatter the veneer and reveal the core. It's like when a pebble hits a windshield and shatters it."

Marshall suggested that Nowak sought revenge for the lack of a romantic relationship with Oefelein.

"Once a psychological crisis happens, it exposes the primitive part of the mind that seeks revenge when love is taken away," she said.

If Nowak was mentally ill, NASA might not have known about it.

"If this is a case of 'psychotic core' -- the illness wouldn't be visible until that pebble shattered the windshield," Marshall said. "But it's also possible that she came down with a mental illness, such as bipolar disorder, recently. In that case, NASA wouldn't have detected the condition because she didn't have it yet."

Astronaut Turned Stalker?

Nowak's behavior resembles that of a stalker. If not from mental illness, her pursuit of Oefelein's girlfriend could have stemmed from a latent stalking personality.

"People don't usually suddenly become stalkers in their 40s. It's a pattern of behavior that usually begins earlier in adulthood," Marshall said. "But it's something that's more likely than a mental illness, like bipolar disorder, to go undetected for years. So she could have had a stalking-type personality for a long time, but people didn't know it."

Marshall explained that stalkers have a very primitive way of thinking.

"Stalkers are very primitive. They're stuck in a two- or three-year-old's way of thinking. Adults understand that other people have their own needs and separate concerns. Stalkers, on the other hand, are profoundly immature," she said. "But unlike mentally ill people, like those who are bipolar, their actions are premeditated. They know exactly what they're doing and they choose to indulge it."

Marshall stressed that to truly understand the case and what motivated Nowak's behavior, it's necessary to know more about her relationship with Oefelein.

"What fits the stalking typology is if the person has a fantasy of being loved by someone else who in actuality doesn't love them in return," she said. "They want to strike out at the love object, but sometimes they will strike out instead at the third party who, in their fantasy, is obstructing that love."