Roughly a year and a half after a TDP MLA was caught allegedly trying to bribe another legislator, the Telangana Anti Corruption Bureau (ACB) on Monday told the Hyderabad High Court that it could not identify the source of the Rs 50 lakh cash that was seized.

The court was hearing a petition filed by Andhra chief minister N Chandrababu Naidu, challenging an ACB court's order, which sought a probe into his reported role in the case.

Stating that the ACB was still in 'pursuit of the truth', the Times of India quotes the Bureau's counsel as saying, "We are on our job. The investigation is still continuing...We are collecting evidence and getting it examined through scientific methods. Since this is a high profile case involving bigwigs, we are treading it carefully and collecting evidence that will stand the test of the court and time."

Last month, an ACB special court in Hyderabad ordered a re-investigation into Naidu's role in the case, after a complaint by YSRCP MLA Alla Ramakrishna Reddy, who alleged that the Telangana government had failed to bring the case to a conclusion.

The court had then directed the ACB director-general to conduct a probe and submit a report. 

However, Naidu petitioned the Hyderabad HC to quash the ACB order. Following this, the YSRCP MLA moved the case to the Supreme Court, which asked the Hyderabad HC to take a decision on Naidu's petition within four weeks.

Telangana TDP legislator Revanth Reddy was arrested by the ACB on May 31, 2015, for offering Rs 50 lakh to nominated MLA Stephenson in order to make him vote for the TDP-BJP candidate in the elections to Telangana's legislative council. 

ACB, which had laid a trap on a complaint by Stephenson, also arrested Revanth Reddy's aides. 

The ACB had earlier said that there were 102 telephone conversation records in another accused TDP leader Bishop Harry Sebastian's phone related to the case.

However, the most important phone call was one alleged to be between Stephenson and Naidu.

The audio tape was first played by T News, a Telugu news channel owned by ruling TRS and was later picked up by others. 

During the conversation, Naidu purportedly assured the nominated member that he is with him. "Our people briefed me. I am with you don't bother. For everything I am with you. What all they spoke we will honour (sic)" Naidu was allegedly heard as telling the legislator.