The future of the Australian Border Force Commissioner, who has been on highly paid leave for nine months, now rests with the Attorney-General after two separate inquiries into Roman Quaedvlieg's personal conduct.

Key points: Border Force Commissioner has been paid more than $500,000 on leave while under investigation

Border Force Commissioner has been paid more than $500,000 on leave while under investigation The report into Roman Quaedvlieg was given to the AG earlier this month

The report into Roman Quaedvlieg was given to the AG earlier this month Labor is now demanding answers about the lengthy process

Commissioner Quaedvlieg has accrued about $500,000 in salary payments since going on leave in May, when an external investigation into his personal conduct began.

At a Senate Estimates hearing yesterday, Department of Home Affairs Secretary Mike Pezzullo revealed the Australian Commission for Law Enforcement Integrity (ACLI) delivered its findings into the case of Commissioner Quaedvlieg in "the third quarter of last year".

But late yesterday the Department of Prime Minister and Cabinet (PM&C) revealed that Secretary Martin Parkinson had handed the findings of his own inquiry to Attorney-General Christian Porter on February 5.

In a statement, Mr Porter said Prime Minister Malcolm Turnbull asked him, rather than Home Affairs Minister Peter Dutton, to make a final decision on Commissioner Quaedvlieg's fate.

"This is to prevent any apprehension of bias given Mr Quaedvlieg's reporting obligations to Minister Dutton under the Australian Border Force Act," Mr Porter said.

"As a result of this request, and before receiving Dr Parkinson's report, I sought legal advice from the Australian Government Solicitor to satisfy myself that I can consider and determine this matter.

"On 5 February this year, I received Dr Parkinson's report which contains findings and recommendations that will assist me in considering this matter."

The ABC has been told the Government is keen to finalise the matter as soon as possible, but the Attorney-General said he would "not be making any further comment" during his consideration of the report.

Labor senator Penny Wong is demanding answers over the protracted investigation into Commissioner Quaedvlieg's conduct.

"Cleaners in Parliament House don't get this sort of treatment do they?" Senator Wong said during the Senate Estimates hearing.

Porn Twitter 'like' remains a mystery

The Senate committee has also been told the person responsible for "liking" a pornographic clip from Commissioner Quaedvlieg's official Twitter account remains a mystery.

In July last year, two months after Commissioner Quaedvlieg took leave from his post as Border Force Commissioner, his Twitter account liked a tweet containing an explicit video.

Rachel Noble from the Department of Home Affairs said an ACLI investigation had been unable to determine if the action was deliberate or if the account was hacked.

"They found no evidence that Mr Quaedvlieg had used the official ABF Commissioner's Twitter account to like a tweet containing a pornographic clip from an account under the name 'Lady Mystique'," she said.

"ACLI also found no evidence of who had liked the tweet or whether the like was accidental or intentional."