Dr. Nash Denic, seen in this 2008 image, has resigned as laboratory chief at Eastern Health. (CBC)

The St. John's physician who resigned amid a controversy over lab testing at Newfoundland and Labrador's largest health authority wanted to quit three months ago because of an excessive workload, CBC News has learned.

Meanwhile, two more lab managers have resigned at Eastern Health, the embattled authority announced Thursday evening.

Dr. Nash Denic's resignation as chief of laboratory medicine at the St. John's-based authority was announced Wednesday as CEO Vickie Kaminski announced disciplinary action over mishandling of biochemistry lab tests.

On Wednesday, Kaminski said Denic had accepted responsibility for not having filed appropriate paperwork on mistakes involving tests for cyclosporine, an immunosuppressant used in a variety of patients. Some patients received too much cyclosporine, which can cause kidney damage.

"Dr. Denic understands that he did not fulfil his obligations under occurrence reporting and he had offered his resignation, and today we accepted that," Kaminski told reporters Wednesday.

Kaminski's wording has proven to be significant, as CBC News has learned Denic tendered his resignation in December, months before the cyclosporine issue surfaced.

Colleagues tell CBC News that Denic had wanted to quit, mainly over workload problems. At the time, Eastern Health asked him to withdraw his resignation for a three-month period so the authority could find a successor.

Feels like scapegoat

Colleagues said Denic now is angry and feels like a scapegoat, given this week's events, which included Health Minister Jerome Kennedy warning senior managers in the health-care system they may be fired if they don't live up to higher expectations of accountability.

Eastern Health CEO Vickie Kaminski said Thursday that two laboratory site chiefs have also resigned. (CBC)

Denic is refusing to comment.

"Eastern Health will not be providing further comment on Dr. Denic's resignation at this time," the authority said in a statement to CBC on Thursday, although Kaminski had acknowledged Wednesday that Denic had raised other issues.

Meanwhile, problems at the authority's labs were compounded Thursday evening as two site chiefs in laboratory medicine resigned from management positions.

One of them, Dr. Ford Elms had been both the site chief at the Health Sciences Centre and the director of the immuno-histochemistry laboratory. The other, Dr. Don Cook, had been site chief of laboratory medicine at St. Clare's Hospital in St. John's.

It is not confirmed whether Elms or Cook resigned in support of Denic.

"I want to clarify that these individuals have resigned from their leadership roles as site chiefs, not as employees of Eastern Health," Kaminski said in a statement.

The authority said it will not provide "any specific details" on the latest resignations, including what prompted them.