THE BRONX - A former Bronx Science biology teacher and her companion drove to the middle and jumped off the Tappan Zee Bridge yesterday in what police say could have been a suicide mission.

Alfa Choice, 29 - a former teacher at Bronx High School of Science - died in the morning plunge, while her companion, Christopher Shears, 44, survived but is in critical condition.

An investigation into what prompted them to jump is ongoing.