The cross-examination of the fourth defence witness in the ongoing Samreboi illegal mining case involving Bernard Antwi Boasiako, popularly known as Chairman Wontumi, and two others, has concluded.The witness, former Western Regional Minister Kwabena Okyere Darko-Mensah, came under questioning over his knowledge of the events surrounding the assignment of a mining concession at the centre of the criminal trial.During cross-examination, Darko-Mensah admitted that he had no personal knowledge of discussions between Chairman Wontumi, the first accused person, and Henry Okum, a prosecution witness, regarding the assignment of the Samreboi concession.The alleged assignment forms a key part of the charges currently before the court.According to the proceedings, the former Minister acknowledged that he was not privy to what transpired between the two parties when the concession was allegedly transferred.The admission came as the defence continued presenting its case in the matter.Meanwhile, the accused persons have filed a witness statement for a fifth defence witness, identified as Evans Addae.The defence is expected to call Mr Addae to testify when the case resumes on Wednesday, June 3.Chairman Wontumi and the two other accused persons are standing trial on allegations of illegal mining in the Samreboi area.The case continues before the court.