Plaintiff Karen Clark says she has still not had any closure after her mother's death. (David McKie/CBC)The lawyer representing families in a lawsuit seeking damages from Maple Leaf Foods, whose Toronto meat processing plant was linked to a listeriosis outbreak that may have claimed the lives of up to 20 people, told CBC News the death toll might be even higher.

Tony Merchant, of the Regina-based Merchant Law Group, represents about 4,200 people in the class action suit against Maple Leaf in six provinces.

He told CBC News an affidavit from one of the lead plaintiffs filed on Monday suggests that more people may have died during the outbreak of the illness, caused by the bacteria Listeria monocytogenes.

Timothy Clark's mother, 89-year-old Frances Clark, died of listeriosis on Aug. 25. The affidavit states she consumed Maple Leaf black forest ham at Belleville General Hospital while receiving treatment for a fall on separate occasions between mid-July and early August.

The affidavit, filed by the resident of Madoc, Ont., said Belleville health officials confirmed his mother's nursing home subsequently served Maple Leaf meat to residents between Aug.7 and 15.

That the nursing home served the tainted meat to other residents before the recall suggests still more could have died as a result of consuming the meat, said Merchant.

He also points to one affidavit that cites a report written by Dr. Robert Bortolussi, a pediatric infectious disease specialist from Halifax.

Bortolussi said it is reasonable to assume that the number of the deaths in the outbreak were higher, partly because of a dearth of testing for listeria.

"I have also had that belief and suspicion flowing from difficulty that people had getting testing done – difficulty that people had in obtaining the tests that had been done," Merchant told CBC News.

Maple Leaf should have recalled products sooner: plaintiff

The Canadian Food Inspection Agency (CFIA) informed Maple Leaf Foods on Aug. 12 that a formal investigation had been launched into the company's products and a day later, Maple Leaf warned its distributors to put its products on hold, pending the results of the investigation.

After receiving positive test results for the listeria bacteria on the evening of Aug. 16, Maple Leaf began a massive voluntary recall of its meat products the next day.

But Clark says in the affidavit Maple Leaf "should not have put this killing product in the marketplace," and should have recalled the tainted products sooner.

"Earlier disclosure by Maple Leaf could have … saved my mother's life," he said.

His sister, Karen Clark, who is also a plaintiff in the suit, said she has vivid memories of the time before her mother's death.

"She was laying there and it was like gasping, like a fish out of water," she said. "It was a horrible gasping for the next day and a half. It was just a horrible thing to watch."

Nursing home meat samples contaminated

A CBC/Toronto Star investigation found that health officials learned about two listeriosis cases in mid-July after two people in a Toronto nursing home became infected, well ahead of Maple Leaf's Aug. 17 recall.

During the investigation, records were obtained showing two-thirds of meat samples taken from Toronto-area nursing homes and hospitals in mid-August for testing were contaminated with the listeria bacteria.

Most of the infected meat products were linked to a Maple Leaf Foods meat processing plant in Toronto.

The daughter of another listeriosis victim, 69-year-old Jeaninne Jacques, who died on July 28 after eating Maple Leaf meat, filed an affidavit chronicling her mother's worsening condition before she passed away.

Linda Gosselin states in her affidavit that her mother first became ill a couple of weeks earlier and was admitted to an emergency room in Smooth Rock Falls, Ont., on July 18.

"I always think about if Maple Leaf had done the recall of their meat products containing the strain of Listeria monocytogenes sooner, medical practitioners may have been able to address the problem at the time," she wrote in the affidavit.

"It is frustrating to think my mother passed away due to the negligence of Maple Leaf, and I do not think that she should have passed away at the age of 69 years old … I believe (Maple Leaf) should be held accountable and their behaviour should change so that no one will suffer like this again."

The lawsuit involves people who have suffered illness, death, mental distress or financial losses as a result of the tainted meat and recall. None of the allegations contained in the suit have been proven in court.

Merchant has said it would take until early next year to determine if the class action would be certified by a judge. There are no dollar figures listed in the suit as plaintiffs continue to come forward.

If the certification is successful, Merchant's law firm would then be the legal representative of anyone making a claim against Maple Leaf in connection with the outbreak of listeriosis, whether they sign on to the suit or not, said Merchant.

Maple Leaf Foods has declined to comment on the lawsuit, but president Michael McCain has said Maple Leaf accepts full responsibility for the outbreak and apologized for his company's role.

With files from David McKie and Rob Cribb