It took almost four months but Prime Minister Stephen Harper has got someone to investigate the Maple Leaf Foods listeria outbreak of last summer.

Just how Sheila Weatherill, former president and CEO of Capital Health in Edmonton, will investigate the outbreak that killed 20 and sickened at least 50 more may be a secret until she reports to Agriculture Minister Gerry Ritz in July.

That’s because Harper has told her not to talk to reporters or hold public sessions.

Liberal agriculture spokesman Wayne Easter said Weatherill’s “resources and powers are too limited to reveal what actually happened. The government has not been transparent with Canadians with regard to this tragedy.”

Health critic Carolyn Bennett said the only way to get to the bottom of the outbreak is through a full judicial inquiry with the power to gather evidence and compel witnesses to testify.

Weatherill’s task is to determine what caused contamination of deli meats from Maple Leaf Foods and what steps should be taken to prevent a reoccurrence, the prime minister said. Her final report will not express findings of criminal or civil liability.

Earlier in January, Maple Leaf announced it would pay up to $27 million in compensation to victims of the listeria outbreak rather than fight class-action suits in court. The court proceedings were expected to reveal a lot about what happened in the Toronto plant that was the source of the contaminated product.

Bob Kingston, president of the Agriculture Union of the Public Service Alliance of Canada, which represents meat inspectors, agreed Ottawa hasn’t given Weatherill “the latitude or power to properly carry out her work.

“She will get information based on the goodwill of the participants who may or may not tell her the full story,” he said in a statement.

He said the union, which has criticized the Canadian Food Inspection Agency for months over meat inspection procedures, wants the Commons agriculture committee to investigate the listeria outbreak. That committee doesn’t meet for several weeks yet.

Weatherill’s mandate will also allow her to examine the role of federal and provincial health and food safety agencies and look at what other countries are doing to prevent listeria outbreaks. A particular focus will be on the effectiveness of CFIA in ensuring the safety of food products.

Weatherill ran Capital Health, a large teaching hospital and health-care facility in Edmonton, from 1996 to 2008.