His body was later fished out by fire brigade officials.
According to police, Rathod, who was into a business, asked his driver to steer his four-wheeler towards Bandra Worli Sea Link bridge.
Upon Rathod's direction, the driver halted the vehicle on the sea link. He then got down on pretext of answering nature's call, but suddenly plunged into the sea, following which police and fire brigade were alerted, said Dhavle.
The fire brigade officials after fishing out the senior citizen, rushed to the nearby Cooper hospital where he was declared dead before admission, police said.
Rathod was under depression due to a prolonged disease and it might have caused him to take this extreme step, Dhavle said, adding, "The victim left a suicide note in which he blamed his illness for ending his life."
An accidental death case has been registered, he added.