An Army official says Tucson massacre suspect Jared Loughner, who wanted to sign up for military service two years ago, was a “habitual drug abuser.”

The revelation brings up the question of whether marijuana played a role in an apparently troubled man's life. While cannabis is legal in California and is sometimes seen as a medicinal panacea in L.A., the pot shop capital of the nation, some say it has a dark side, especially for daily users.