Experts See Professional Jealousy in Yale Killing

Ray Clark could have strangled Annie Le because she was moving on to a satisfying career while he had to clean mouse cages in a lab, criminologists tell ABC News. If Clark is guilty, he may have suffered from what experts call "relative deprivation"—a mindset created "when you are measuring your own self worth against others and you come out on the bottom," says criminologist Jack Levin.

Clark, who has not filed a plea since his arrest this week, has been described as possessive of his fiancée and the mice whose cages he cleaned. Such desire for control is often "underestimated as a motive for murder," says Levin. The killing method, strangulation, further hints that the murder was "a very personal thing," says a former FBI agent. "Think about what anger and rage anyone would have to have."

(More Raymond Clark stories.)