MUMBAI: Sheena Bora murder case accused Peter Mukerjea on Friday walked out of the Arthur Road prison here after spending over four years behind bars.The release came after the six-week stay on the Bombay High Court order granting the former media baron bail in the murder case ended on Thursday with the CBI not moving an appeal before the Supreme Court.That development had removed a major hurdle in the path of Mukerjeas release over four years after he was arrested in the case