"The defendant is accused of committing what is every subway commuter's worst nightmare," he said.
On Dec. 3, another man was pushed to his death in a Times Square subway station. A photo of the man clinging to the edge of the platform a split second before he was struck by a train was published on the front page of the New York Post, causing an uproar about whether the photographer, who was catching a train, or anyone else should have tried to help him.
A homeless man was arrested and charged with murder in that case. He claimed he acted in self-defense and is awaiting trial.
It's unclear whether anyone tried — or could have tried — to help Sen on Thursday.
Mayor Michael Bloomberg on Friday urged residents to keep Sen's death in perspective as he touted new historic lows in the city's annual homicide and shooting totals.
"It's a very tragic case, but what we want to focus on today is the overall safety in New York," Bloomberg told reporters following a police academy graduation.
But commuters still expressed concern over subway safety and shock about the arrest of Menendez on a hate crime charge.
"For someone to do something like that ... that's not the way we are made," said David Green, who was waiting for a train in Manhattan. "She needs help."
Green said he caught himself leaning over the subway platform's edge and realized maybe he shouldn't do that.
"It does make you more conscious," he said of the deaths.
Such subway deaths are rare, but other high-profile cases include the 1999 fatal shoving of aspiring screenwriter Kendra Webdale by a former psychiatric patient. That case led to a state law allowing for more supervision of mentally ill people living outside institutions.
Associated Press writer Karen Matthews contributed to this report.