Horrible and callous...but not sure its murder. Manslaughter maybe?
it is premeditated murder...
she waited for him to get on the steps, and then shoved him.
she had a plan, and executed it and him flawlessly.
In most states if you commit a felony that results in someone’s death it can be charged as “Felony Murder.”
"Second degree murder. n. a non-premeditated killing, resulting from an assault in which death of the victim was a distinct possibility. Second degree murder is different from First Degree Murder which is a premeditated, intentional killing, or results from a vicious crime such as arson, rape, or armed robbery.
Only reason I wouldn't call it First Degree, is that she didn't know if he would be killed or severely injured. Didn't care, either, since she then exited the bus and never showed even a flicker of concern for the man lying on the pavement at her feet.