They said documents seized during the searches were being scrutinised in detail.
Further details were awaited.
Kakkad, a former Madhya Pradesh police officer, was appointed OSD to Nath after the Congress-led government came to power in the state last year.
He had earlier served as OSD to former Union minister Kantilal Bhuria during the UPA regime.
Kakkad’s family is associated with a number of businesses, including hospitality.