Kolkata, Sep 14 : The Calcutta High Court on Thursday dismissed an order passed by a lower court for joint investigation into the letter penned by Kuntal Ghosh, an accused in the cash for school jobs case, accusing central probe agencies of pressurising him to name Trinamool Congress' national General Secretary Abhishek Banerjee in the case. Recently, a special PMLA court had ordered a joint probe by the CBI and the Kolkata Police into the allegations levelled by Kuntal Ghosh in his letter, which he forwarded to the judge of the same special court as well as to a local police station. However, on September 11, the CBI had challenged that order at Calcutta High Court's single-judge bench of Justice Sinha, arguing that when the CBI and the ED are already investigating the matter following a clear direction from the high court, what is the justification of a joint probe. After completion of hearing in the matter on Thursday, Justice Sinha observed that there is no need to implement the special court order for a joint probe in this matter. The CBI has already questioned the superintendent of Presidency Jail, Debasish Chakraborty, about the 'prisoner's petition' filed by Kuntal Ghosh, an expelled youth Trinamool Congress leader. The CBI questioned Chakraborty as to whether proper procedures were followed and his approval was sought by Ghosh before making the prisoner's petition. The central agency also sought information about the jail employee who delivered the letter to a local police station and to the office of the judge of the special PMLA court. /IANS