TORONTO -- More visas have been issued for the Canadian officials who will assist in the investigation of the Ukrainian airliner that was unintentionally shot down by Iran, killing all 176 aboard.

In a series of tweets on Sunday, Minister of Foreign Affairs François-Philippe Champagne wrote that visas have been approved for six members of the Standing Rapid Deployment Team (SRDT), who are currently stationed in Ankara, Turkey.

“We expect the Standing Rapid Deployment Team (SRDT) to be fully in place to do their important work by January 14,” the tweet stated.

He also mentioned that visas were given to two experts from the Transportation Safety Board. They will head to Iran on Monday.

The TSB added Sunday evening that it is also sending a second team of investigators to Iran who specialize in “aircraft recorder download and analysis.” The agency will provide more details during a press conference on Monday afternoon.

Fifty-seven Canadians were among the 176 people killed when Iran unintentionally shot down the Ukrainian flight, including 13 from the Edmonton area. Dozens more were bound for Canada, many of whom were students and professors returning from their holiday break.

The Iranian government denied the possibility of the plane having been shot down at first, but took responsibility and issued apologies a few days later, saying the plane was mistaken for a cruise missile.

Retired general Tom Lawson, former chief of the Defence staff, told CTV during Question Period on Sunday that he believed the days of no real explanation from the Iranian government immediately following the crash were a result of Iran believing they were the only ones with the full picture of what had actually happened -- which Lawson said was not the case.

Satellites associated with NORAD would have been aware of Iranian missiles having been fired “within seconds,” he said.

“My experience as deputy commander of NORAD would say that as soon as those missiles left the ground, they were being assessed for their threat to the North American continent. That’s what NORAD does and that’s what those satellites would’ve picked up.”

What caused the delay in Iran putting out an admission of responsibility is one question of many that Canadians will be looking to have answered.

What access investigators will have to all of the evidence is not yet clear. The crash site itself has reportedly been bulldozed, and the debris has been moved.

On Saturday, three Canadian officials with Global Affairs Canada landed in Tehran to begin setting up a “base of operations” for the government.

Canada severed diplomatic ties with Iran in September 2012 and recalled all its diplomats and closed its embassy.

With a file from Writer Ben Cousins