Updated

The Manhattan District Attorney launched a criminal investigation into the horrific New York City elevator accident that took the life of a rising advertising executive, sources said.

Cyrus Vance's office joined the Buildings Department, the Department of Investigations and the police in trying to figure out what caused the tragic death of Brooklyn resident Suzanne Hart on Dec. 14, the sources said Tuesday.

Investigators are focusing on electrical work performed on the elevator by its maintenance contractor, Transel, in the hours before Hart was killed. But they have not yet identified the cause of the accident.

Bad elevator maintenance was a problem at 285 Madison Ave., which is owned by global advertising giant WPP.

In the aftermath of Hart's death, city inspectors wrote 11 violations against the 13 elevators serving the 25-story building.

The only violations on the car that killed Hart, 41, were paperwork problems, but more serious issues were cited on the other elevators.

Hearings on the violations were scheduled for next month.

Click here for more on this report from the New York Post.