The sources said Pratibha has been asked to appear before the investigating officer next week. The agency has attached assets worth about Rs eight crore against the Chief Minister earlier this year. Singh has denied allegations against him and his family.
The agency has filed a case under criminal provisions of money laundering laws after taking cognisance of a complaint filed by the CBI in this regard in September last year. ED had also conducted searches in this case last year in Delhi, Maharashtra and West Bengal.
The agency is probing allegations against Singh and his family members of having amassed wealth of Rs 6.1 crore between 2009-11, disproportionate to his known sources of income, while serving as the Union Minister of Steel.
The CBI FIR (First Information Report) had named Singh, Pratibha Singh, Chauhan and his brother C L Chauhan and they were charged under the Prevention of Corruption Act.
CBI suspects that during the 2009-11 period, Singh allegedly invested Rs 6.1 crore in life insurance policies in his and his family members names through Chauhan claiming this money to be his agricultural income.
It alleged that Singh attempted to legitimise the same as agricultural income by filing revised Income-Tax returns in 2012.