Four people contacted the ACT Greens wanting to share allegations against Johnathan Davis, including a person who said they were 15 at the time, after the member for Brindabella resigned.
The information provided by the person who said they were 15 years-old was referred to police, Legislative Assembly speaker Joy Burch, the Assembly's clerk and the Integrity Commissioner.
All four people were provided with support, including in some cases offers to meet with the Victims of Crime Commissioner.
A review of the way the ACT Greens handled allegations levelled at Mr Davis in November was critical of the party, but found they did not "wilfully or improperly withhold" information.
The report was released on Tuesday, the first Legislative Assembly sitting day of the year.
Greens leader Shane Rattenbury's chief of staff did not understand Commonwealth law made it illegal to share explicit images before the age of 18, the review found.
"I expect that any political party dealing with such an unfolding nightmare would have struggled to know exactly what to do and when to do it, but maybe they would likely have had a stronger eye on managing the risks and the fallout," former Australian Public Service commissioner Lynelle Briggs found.
Mr Davis, who has declined through a lawyer to comment on all allegations put to him, was accused of having sex with a minor and having an inappropriate relationship with a 17-year-old.
The Canberra Times revealed Mr Davis had been stood down by his party over the allegations.
Ms Briggs made a series of recommendations, including that Legislative Assembly members and their staff should be required to report to police within 24 hours any allegations of illegal sexual conduct affecting children and young people.
However, the review found it was "surprising" the Greens' Emma Davidson, a minister, did not report rumours of the allegations to Greens leader Shane Rattenbury or Chief Minister Andrew Barr. Ms Davidson should have taken advice and reported what she heard to Mr Rattenbury and Mr Barr, the review said.
"The Greens thought about the issue at hand from a Greens member's perspective, rather than from the perspective of the member being a member of the government, and their duties as part of the government," Ms Briggs said.
The review also found the Greens were mistaken in assuming they were right to investigate the rumours or allegations levelled at Mr Davis.
"I would go so far as to say that, in hindsight, [Greens executive chief of staff Guy] Bromley should not have met with the young complainant at all and, even with his doubts and concerns about unsubstantiated rumours, he should have reported to the police immediately," Ms Briggs wrote.
Mr Rattenbury had charged Mr Bromley with conducting an internal review "to find out what we were dealing with" and to "do it quickly", the review said.
Mr Bromley met with an 18-year-old complainant on November 7, who provided information about consensual encounters with Mr Davis when he was 16 and 17 and the sharing of explicit images.
"The young complainant found Mr Bromley to be abrasive and interrogating during the meeting and said that he traumatised him as much as a police investigation. He alleged that Mr Bromley was more concerned for Mr Davis and the Greens Party than for vulnerable young people," Ms Briggs wrote.
"Mr Bromley acknowledged to me that there had been a power difference at the meeting and said that he tried to keep the tone reasonable, asking open questions and doing so calmly, albeit that he accepted that he did ask a lot of the young person in pursuit of information."
Ms Briggs' review also said Mr Bromley did not understand Commonwealth and ACT law prohibited sharing explicit images before the age of 18. He advised the review he drew upon a Legal ACT web page titled Is Sexting a Crime?.
The page left Mr Bromley with the impression that "sexting" was illegal only if those involved in the ACT were under 16, the review said.
Mr Rattenbury said in a statement on Friday, November 10: "My office has not seen evidence of illegal activity, but we are reporting what we know of the complaints to police."
The review noted Mr Bromley "said that had he understood that Commonwealth law takes precedence over state and territory law, he would have reported the rumours to police as they would evidently have been an indication of unlawful sexual activity and transmission".
The review noted Mr Bromley was a "relatively new arrival from the UK" who may not have appreciated the interactions between Commonwealth and ACT law. "We can't blame him for that," the review said.
Although 16 year-olds in the ACT can consent to sexual activity, those aged 16 and 17 cannot legally use telecommunications services to exchange illicit messages.
Ms Briggs said: "Decriminalising the actions of young people under the age of 18 who consensually share images electronically would go some way to removing the fears and concerns of young people exploited sexually by older people, but the fact remains that unless they have a safe place to report, unlawful activities will continue to go unreported."
