Calls for probes into Daithí McKay's dealings with leading loyalist Jamie Bryson over Nama evidence
DUP chairman Lord Morrow said he would be referring the matter to the PSNI, as he believed it was part of a "dirty tricks" campaign against his former party leader Peter Robinson, who Mr Bryson claimed was set to benefit financially from Nama's sale of the Project Eagle loan portfolio.
Mr Robinson has flatly denied the accusation.
It is understood the DUP peer is keen to see the former Sinn Féin MLA investigated over 'malfeasance in public office' – a catch-all category for wrongdoing by politicians.
"For some time, the Democratic Unionist Party has had concerns about the nature of the inquiry, how it was conducted and the way witnesses from the party, including the then first minister were treated," Lord Morrow said.
"It is clear from what is already in the public domain that what occurred is an abuse of the process and the privilege of the committee and it was used to besmirch the good name of the then first minister and party leader Peter Robinson."
Alliance deputy leader Naomi Long said the only way to restore public confidence in Stormont was through an independent probe.
She noted how Alliance had previously raised concerns about Mr Bryson’s evidence to the committee, which Mrs Long said always had the potential to be "politically motivated or otherwise unreliable".
The East Belfast MLA also voiced scepticism that Mr McKay had acted without the authority of the Sinn Féin leadership.
"There are other questions which also need asked, such as if the other Sinn Féin members named in the social media messages printed in the media today had any involvement in this episode," she said.
"It’s right those questions are asked and it’s right an independent investigation is held into this entire matter in order to attempt and restore public confidence in politics."
The assembly's standards commissioner can also investigate the matter, though as Mr McKay has now resigned, a complaint would need to be made within the next four weeks in order to trigger a probe.