However, special patient orders have a limit of 10 years and Lyall's is set to expire in December.
Last week the Herald revealed that the Waitemata District Health Board - who oversee the Mason Clinic - had asked the director to seek a court order that would give it much tighter, continued control over the alleged murderer.
The DHB want the director to apply for Restricted Patient Order (RPO) through the courts which would keep Lyall under its care indefinitely.
According to the Mental Health Act, restricted patient status may be imposed on an inpatient - which Lyall is, though he lives part-time in the community - who presents "special difficulties because of the danger he or she poses to others".
Mason Clinic director Dr Jeremy Skipworth said the orders were "very rare".
There are only eight other people in New Zealand currently subject to an RPO.
"But it is the opinion of our expert clinicians that it is appropriate in Mr Lyall's case," Skipworth said.
Director of Mental Health Dr John Crawshaw told the Herald that he was now working with the DHB "to consider options regarding Mr Lyall."
However an application for the RPO could not be filed yet.
"As Mr Lyall is currently held as a special patient, there is no authority under the Mental Health (Compulsory Assessment and Treatment) Act 1992 for any application to be made to the Court at this time for him to be made a restricted patient.
In the future, if Mr Lyall is no longer a special patient but is instead subject to an in-patient order under the Act, consideration could be given then as to whether any application be made for Mr Lyall to be declared a restricted patient.
A Ministry spokesman confirmed that once the SPO lapsed, the case would go before the Attorney General, who could direct Lyall remain an in-patient at the Mason Clinic under a Compulsory Treatment Order.
Once that was in place, the Ministry could apply for an RPO.
In the meantime, Crawshaw would continue to work with the DHB.
Last week Criminal law and psychiatry expert Professor Warren Brookbanks of AUT told the Herald that the move towards and RPO suggested that Lyall was considered dangerous.
"This would suggest in Mr Lyall's case that his mental health status is considered by clinicians to present such a high risk of a particularly difficult nature that other people would be in danger if he were not subject to a restriction order," he said.