Maria Hawthorne, Ms Burch's former chief of staff, was cleared of criminal conduct as it emerged that a second unnamed ministerial staffer was implicated in leaking sensitive police operational material to outsiders. Ms Hawthorne remains distraught, saying her career and reputation have been destroyed by the "painful" affair.

Ms Hawthorne says she and Ms Burch had been "thrown under the bus" by Chief Police Officer Rudi Lammers and the Barr government.

"We just got caught up in a bad political situation," she said.

"We didn't like the way that ACT Policing dealt with our office, they didn't like the way that we dealt with them and we got taken down. This is what is unprecedented about it – that a police officer gets to decide who is a minister and that is totally against the Westminster system."

Chief Minister Andrew Barr confirmed the second staffer was still employed in the ACT Assembly, although not by a minister. Ms Burch is one of only two backbenchers. Mr Barr said the conduct of non-ministerial employees was a matter for their bosses, and Ms Burch refused to comment on her staff.

Assistant Commissioner Lammers said no criminal conduct had been uncovered and no charges would be laid after the three-month investigation.

He said police were concerned about the handling of sensitive police information in Ms Burch's office throughout 2014, from April when police became aware of a conversation between Ms Hawthorne, and Construction, Forestry, Mining and Engineering Union ACT secretary Dean Hall.

In the conversation, believed to have been recorded by the royal commission into trade union corruption, Ms Hawthorne briefed Mr Hall on a meeting between Ms Burch and Assistant Commissioner Lammers.

Assistant Commissioner Lammers said there had been ongoing releases of sensitive information later in the year. It is not clear what information the second staffer passed on and to whom, but Assistant Commissioner Lammers said it was "sensitive police operational information" not related to the union issue.

"The evaluation found that there were other instances where confidential police information was released to people who had no need to know the information," he said.

"There are a number of instances but I won't be discussing the specifics because they do relate to ongoing police investigations ... there are matters separate to the CFMEU that were related to people who didn't need to know that information."

When police concerns became public in December, Ms Hawthorne was forced to resign and Ms Burch lost her ministerial position.

Assistant Commissioner Lammers briefed Mr Barr and Police Minister Simon Corbell on the results of his evaluation last week. He did not explain why his public announcement was delayed till Tuesday, but Mr Corbell confirmed the government was involved in the timing and had sought legal advice.

Mr Barr said the police had made suggestions about staff training and handling of sensitive information that he would now consider. He would not elaborate on what he has been told about repeated leaks of sensitive government information last year.

"The chief police officer outlined … the nature of the police evaluation. I've got nothing further to add to that. I'm not privy to the full police evaluation, I was not conducting it," he said.

Mr Hall called on police to make the recording of his conversation with Ms Hawthorne public.

"I was in the witness box at the trade unions royal commission for two-and-a-half days and the record of that conversation was never played to me nor was it referred to," he said, in turn calling for a royal commission "into the conduct of the AFP in this investigation and its interference in the political process".

Opposition Leader Jeremy Hanson said Mr Barr owed the community "a full and detailed investigation of what's gone wrong at the heart of the government".

"What I want to know is who provided the information, what information was leaked, who was in receipt of that information, what that group or individual then did with that information. And I share the police concerns about the way this whole matter has been handled."

Ms Burch said she had always been confident there was no criminal misconduct.

"I consider the matter closed," she said.