It follows a damning report into the Tawel Fan ward at Glan Clwyd Hospital.
Simon Dean, interim chief executive of Betsi Cadwaladr health board, confirmed nine staff have been reported to the Nursing and Midwifery Council and three to the General Medical Council.
He will give an update on action being taken at a meeting on 11 August.
Nine members of staff have been suspended, another four redeployed and three placed on restricted duties.

Flanker Davies, 25, was a key player as Team GB claimed a silver medal in the rugby sevens in Rio.
New Zealander Pivac credited Davies with a key moment in helping GB beat Argentina in a tense quarter-final, and expects him to be pressing for a first Wales 15-a-side cap.
"He's always been knocking on the door, he's there or thereabouts," said Pivac.
"There are three or four good sevens (openside flankers) in Wales - it would depend on the style of game that you play.
"James suits an open style of game with a lot of running and a lot of ball movement.
"So if that's the way Wales are going, he's suited. But he's not the only one in that position that can do that."
Davies was selected for the Olympics after being omitted from Wales' squad for the summer tour of New Zealand.
After receiving his medal in Rio, the player jokingly thanked Wales coach Warren Gatland for not selecting him.
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Pivac has coached at World-level sevens but says he has not dealt with an Olympic medallist in the past.
He said Davies would be given a break before returning to training, but was looking forward to seeing him "because he's a character at the best of times."
Team-mate Scott Williams expects the flanker - younger brother of Scarlets and Wales centre Jonathan Davies - to turn up for his first training session wearing the medal.
Asked the region were proud of Davies' achievement, Pivac replied: "Immensely so."
"It's the first rugby sevens at the Olympics, the biggest stage.
"When you listen to all the successful GB athletes each night, talking about how proud they are and how their families are so proud of them - they want to make their country proud and James is no exception.
"He played a big part in that."
Pivac added Davies' strengths as a 15-a-side player had made him a key player for GB sevens team particularly in their nail-biting 5-0 sudden death win against Argentina.
"I think it's his 15-a-side skills, the ones that he's very good at, transferred well into sevens," Pivac said.
"His work at the breakdown is what he's known for in 15s and he was exceptional in gaining turnovers for his team in Rio - either straight turnovers or holding-on penalties against the opposition.
"His defence under the goal-posts against Argentina in the quarter-final allowed the side to get into the medals."
The number of staff reported to their professional bodies over care at a Denbighshire mental health ward has risen to 12.
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Scarlets coach Wayne Pivac says the region are "immensely proud" of Olympic silver medallist James Davies.