On December 1 he contacted a 20-year-old woman from Christchurch whom he had also never met. Over the next five days he sent her some 250 text messages, some of which were abusive.
A third criminal harassment charge was dropped by police. Green was remanded in custody until sentencing in June.
Former TVNZ reporter Charlotte Bellis was said to be among the Christchurch women who received messages from a Glenn Castellano proposing a relationship or meeting.
A leading expert said Green's offending did not fit the four typical profiles of a "stalker".
Paul Mullen, a professor in forensic psychiatry at Melbourne's Monash University, said most cases involved personal relationships - spurned lovers, incompetent suitors, the vengeful and those who pursue their perceived "true love" were the four typical forms of harassment.
The first three types of stalkers were almost always men and the fourth usually women, Professor Mullen said.
However, Green did not appear to fall into one category and instead "crossed boundaries" and was possibly mentally ill. "He sits on the edge. This man's not typical."
Green's first known victim was a 16-year-old he bumped into on a bus. He discovered her name from a bus pass and managed to track down her address to pursue her.
