"Both the Congress and the BJP-led National Democratic Alliance have, in one way or the other, allowed this mystery to remain unexplained. This, in itself, gives credence to (key accused) Kim Davy's allegations," CPI-M Politburo member Sitaram Yechury said.
In an editorial in the party organ People's Democracy, he said while Congress was "in its typically petty manner crying hoarse that these revelations have come at this time to damage the prospects of its alliance with TMC", Mamata Banerjee herself "was then a member of this cabinet" when Bleach was released.
"It is absolutely essential in the interests of India's security to ensure that this extradition happens and Davy is produced before the Indian courts and is duly punished.
"It is equally important that various lapses that have occurred must be investigated and all questions concerning the complicity of the then Congress central government and the circumstances leading to the presidential pardon to Peter Bleach by the then BJP-led NDA government, must be unambiguously answered in the interests of Indian democracy," Yechury said.
He said this must be done by immediately constituting a judicial enquiry into all these circumstances. "No attempt to undermine our constitutional scheme of things can be allowed or permitted," he said.
Terming it as "bizarre and unexplained" the decision by the NDA government to release Bleach under a presidential pardon, he said, "Incidentally, the TMC chief (Mamata Banerjee) was then a member of this cabinet when this decision was taken.
"This decision by the NDA government came in the background of a series of statements made earlier that there was no question of any acceptance of Bleach's plea for clemency," he said.