Here's a snip from an article;
~Colleagues offer sharply different appraisals of her work. "She was superb," said one senior retired intelligence officer. Another dismissed her as "very weak" and prone to depression. Laughter was foreign to her.
"She's certainly not a warm person," said Edward Gonzalez, a retired UCLA professor who knew her. "She is not a happy person. She was always scowling."
The daughter of a military psychologist from Puerto Rico, Montes is a U.S. citizen who was born in Germany and educated at top schools in the United States. She spoke Spanish fluently. She obtained a master's degree from the prestigious School of Advanced International Studies at Johns Hopkins University.
Though she knew many people, she left little wake.
"We're trying to reconstruct who her friends were, and we can't," said Riordan Roett, director of Western Hemisphere Studies at the university. Roett said he only "vaguely" can recall Montes, even though her transcript shows she took two of his classes.
In 1985, Montes got a job as a junior analyst at the DIA, which provides the Pentagon with military and political analysis. A supervisor there at the time, who spoke on condition of anonymity, remembered Montes for her introverted nature.
"She was very private. She never attended parties. When we had office parties, she might show up for only a little while. She'd never bring a boyfriend," he said. ~Snip
The rest of the article is Here
Sounds to me as though she was sexually/socially frustrated. Just a guess though. I hope they hang her.