Hidetsugu Aneha's wife committed suicide by throwing herself to her death from a housing complex near the family home.
Aneha is facing criminal charges for falsifying quake-resistance data for at least 82 buildings - mostly apartment blocks and hotels - to make them appear to meet safety regulations.
He has admitted responsibility for the falsification. Aneha, who is fully qualified and certified, has warned that the buildings, which are now inhabited, could be completely destroyed by a major earthquake.
Japan, which is sited on one of the most active tectonic faultlines in the world, has stringent structural regulations and has understandably responded to Aneha's admission with horror.