Most are working on contacting and interviewing those who had come forward, with assistance from the police electronic crime lab in Auckland, which is going through seized material.
"The process of identifying potential victims and linking these to the information we have obtained is ongoing, and likely to take some time," he said.
"However, we encourage anyone that may have information that could be relevant to please come forward."
Further charges were likely to be laid during Harris' next court appearance on Thursday, Mr Johnston said.
Harris faces 39 charges, including aggravated wounding by allegedly drugging victims to facilitate an indecent assault, making of intimate visual recordings, possession of intimate visual recordings, and indecent assault, relating to 16 victims aged between 18 and 25.