Kirti Ambani is the main accused in the case.
Wadia told the special judge H S Mahajan during his deposition that during 1987-89, when his son was studying in Himachal Pradesh, he was informed one day that his son faced a risk of getting abducted.
After this he sent his son to England, he said.
The court has restrained the media from publishing certain parts of the deposition.
Initially, the case was with crime branch of Mumbai police but later the state government transferred it to CBI.
In 2014, Wadia had moved the court, seeking permission to depose as a witness as he was the victim.
Ambani had applied to the court seeking that Wadia's statement should be recorded in-camera but the court rejected it.