The PSNI has launched an investigation into the clinical practice of a former consultant neurologist at the heart of Northern Ireland's biggest ever medical recall scandal.
The case centres on the work of former consultant neurologist at the Belfast Trust, Michael Watt between 1998 and 2017.
He also worked in private practice.
Concerns over his practice led to the biggest ever patient recall in Northern Ireland with more than 4,000 patients attending review appointments.
A fifth were found to have been given an "insecure" diagnosis.
Patients reported misdiagnosis, the misprescribing of often toxic medicines and the use of invasive and unnecessary medical procedures.
Police said today that 20 patients or relatives of deceased patients had contacted them with allegations.
They now want to hear more patient accounts to establish if any of Mr Watt's behaviour meet the criminal standard for prosecution.
They have not yet spoken to him but they have engaged with his legal representatives.
A public inquiry found that opportunities to address serious concerns had been missed as far back as 2006. It made more than 70 recommendations.
Mr Watt was restricted from practice in 2017 and an initial request by him for voluntary removal from the medical register was approved.
But several of his patients took a legal challenge on the basis that allowed him to avoid a public hearing over fitness to practice allegations.
The courts ruled in their favour, an investigation was undertaken by the General Medical Council and earlier this month he was struck off.
Investigators said it was the only way to protect patients and maintain public confidence.
Former patients demanded a formal police investigation.
Mr Watt has consistently declined to comment, with lawyers citing concern for his mental health.
