LAPD Deputy Chief Kirk Albanese told the Los Angeles Times it was unclear whether attacker spoke to the woman before allegedly setting her ablaze.
There was no incident or dispute or clear motivation for this horrific attack. He did not know his victim. It defies explanation, Albanese said. He is not of sound mind. ... The motive is mental illness.
http://www.foxnews.com/us/2012/12/2...ze-as-lay-on-la-bus-bench-defies-explanation/
I suppose easy access to lighters caused this attack.