Sozo Kanda, the former board member of Japan Highway Public Corp. arrested Tuesday by the Tokyo High Prosecutor's Office, allegedly played a central role in what has become the nation's biggest public works bid-rigging scandal.

Prosecutors suspect the 70-year-old's immense influence stemmed from the companies' acceptance of his "amakudari" status, and from Kanda's ability to contact other Japan Highway retirees, allowing him to influence private companies.

Amakudari, which translates roughly as "descent from heaven," has long been criticized for cementing the shady ties between the public and private sectors and allowing former bureaucrats to use their clout to cash in on years of government service.