Outgoing NT Senator Sam McMahon used her final speech in Parliament to accuse her former chief of staff of “abuse” and “terrorising” her office, stating that she needed “professional assistance to overcome the anxiety and PTSD it created”.

Ms McMahon, who resigned from the Country Liberal Party in January citing fears for her safety after the party refused to take action on the former staffer, used parliamentary privilege to provide further details about her stated reasons for leaving.

“My reason to resign was driven entirely by my former staff member Jason Riley, who did abuse and terrorise my office, including myself,” she said in the Senate on Wednesday, adding that he remained in a role with the party after leaving her office.

“To have to sit in meetings with such a person was stressful, a very stressful experience, and one that has not been without me seeking out professional assistance to overcome the anxiety and PTSD it created.”

Ms McMahon was investigated by the party and the police for a physical altercation involving Mr Riley in 2020, but no charges were pursued.

Mr Riley did not respond to the NT Independent’s requests for comment.

Ms McMahon lost preselection in a party vote to Jacinta Price last July.

Her resignation from the CLP in January threw the party into turmoil, and eventually sparked a review by the Australian Electoral Commission into whether the party had enough members to remain as an official federal party.

While that review is ongoing it is not expected to be completed before the upcoming election, which means the CLP will continue on as a registered party. The review would ultimately end if the party is successful in getting one member elected to Parliament.

Ms McMahon raised the recent passing of Labor Senator Kimberley Kitching, who died of a suspected heart attack amid allegations of bullying within her party, in her valedictory speech, calling for an end to “cruel behaviour” in politics.

“The reported treatment of her by her Labor colleagues greatly saddens me,” Ms McMahon said.

“Whether or not it contributed to her death is a matter of speculation and it will likely never be determined.”

Ms McMahon said she had been subjected to “a vicious display of victim blaming” by another former senior staffer who she did not name.

“This public attack was female on female, as are the allegations surrounding Senator Kitching,” she said.

“It seems it’s not a man thing, a faction thing, a party thing, but it certainly can be a political thing.”

Senator McMahon said she wanted to raise the issues as a learning experience, rather than a point-scoring exercise.

“I think of the premature death of my colleague Kimberley Kitching and one thing that haunts me is that so easily could have been me,” she said.

“We can honour her memory by not making this a political issue, but by fixing it, so politics is a better place, particularly for women.”

Last December, Ms McMahon was accused of attempting to punch the federal director of the Nationals at a party Christmas function. Leader Barnaby Joyce later confirmed the incident occurred but because Ms McMahon offered a “contrite” apology, it would not be investigated further.