Mishar said Raj's lawyers requested the court to allow the MNS chief to travel in the prosecutor's car to the police station as a security measure.
"The court allowed it but asked me to accompany Raj in his car. So I travelled along with the investigating officer," Mishar said.
Questions have been raised about Mishar's travel in Raj's Toyata Land Cruiser after a Kalyan court remanded the leader in connection with the case of alleged assault on North Indians appearing for a railway recruitment examination.
"In a sensitive matter where eyes of people are set on important aspect of the case, it is indeed unbecoming of a prosecutor to sit in the car of the accused to be transported to the police station or the court," said noted lawyer Majeed Memon.
"Such acts raise undue suspicion with regard to the fairness of the prosecution and a possible collusion between the two rival sides," he said.
"The prosecutor ought to have been careful to physically distance himself from the accused when he is expected to present the other side of the case," Memon added.
Another lawyer, Sushant Kunjuraman, said the conduct of a prosecutor should be that of an independent officer of the court.
"It appears that laws are meant only for the poor while those who have money power and muscle power get away easily," he said.
Raj was on Monday arrested in connection with the riot case after he surrendered before a local court which released him on bail on the condition that he would not make provocative speeches.
Raj was booked in a riot case along with seven others for alleged assault on north Indian youths who had come to Mumbai to appear for railway recruitment examination on October 19 last year.
Raj surrendered before the Kalyan court in keeping with a directive of the Bombay High Court which on June 16 had set aside anticipatory bail granted to him by a lower court last year in the case.