The family members submitted a letter to the secretary of Kamduni Pratibadi Mancha (KPM) yesterday in which they said they were "totally frustrated" with the way Mancha was handling the issue.
"Using our family as a front, some political leaders and a section of the media are trying to malign the image of Mamata Banerjee and misguided us entirely. We have total faith in the assurances given by the CM. Thus we withdraw our membership from the Mancha," the letter said.
The family members also alleged that some KPM leaders were more busy in reaping political and personal benefits from the issue than standing beside the helpless family.
Last Saturday, the family members, accompanied by Food and Supplies Minister Jyotipriyo Mullick, met the CM at the state secretariat demanding a speedy trial in the case.