A former CBI director who had investigated the disproportionate assets case against the RJD chief Lalu Prasad and Rabri Devi on Thursday questioned why the Centre did not make any appeal when there was a "water-tight case".

“The case was really strong because it was filed under Prevention of Corruption Act against a public servant. It surprises me that the Centre did not take any initiative to appeal,” former CBI director Upen Biswas told PTI here.

“The CBI has a very elaborate system of investigation. Before filing a case, the agency does a preliminary inquiry and then on the basis of that inquiry a collective decision is taken after examining the legal aspects of the case,” Mr. Biswas said.

“It also requires sanction for prosecution from the Governor. In the case, which was a water-tight one, all procedures were strictly followed and an over 200-page chargesheet was filed against the then Railway Minister in court,” he said.

“The court acquitted him mainly on the evidence of Income Tax return, so the Central government and the CBI should have challenged the acquittal,” Mr. Biswas said.

“That they did not surprises me,” he said.

The former CBI director said the Supreme Court was justified in holding that the Bihar government did not have the authority to file an appeal against the acquittal of the RJD chief and his wife.

“The reason is purely legal and has got nothing to do with the merit of the case,” he said.

He pointed out that the CBI could not make a suo moto appeal and it was the Central government’s jurisdiction to appeal through the investigating agency, which did not do so.

The Supreme Court upheld the RJD chief’s appeal because the Bihar government was not a competent authority to file an appeal in the case, he said.