OTTAWA -- Hours before stepping down as Canada’s chief of defence staff, Admiral Art McDonald invited members of the Canadian Armed Forces to come forward if they have information about military misconduct, vowing to lead the culture change from inside.

Late Wednesday night Defence Minister Harjit Sajjan announced that McDonald “voluntarily” stepped aside while a military police investigation into unspecified allegations of misconduct against him is ongoing.

While it remains unclear precisely when McDonald learned of the investigation into his conduct as he has not commented publicly, Sajjan told CTV News Channel’s Power Play on Thursday that he learned “recently” and McDonald learned “as of yesterday.”

In an email sent to members of the military and obtained by CTV News, McDonald wrote that if anyone was considering sharing information on any case of alleged misconduct within the ranks, “you have my support to come forward.”

Offering information about available supports and avenues to report if going directly up their chain of command is not something they feel comfortable doing, McDonald wrote that anyone who speaks up “can expect to be heard, supported, and protected.”

“Our institution can no longer put the burden of change and transformation on those affected by harassment, discrimination, or any form of misconduct. That burden must rest on us. All of us,” he wrote. “It is critical for all of us to assume collective responsibility for the culture change necessary to make our shared institution a safer and more respectful workplace for all.”

Facing calls from the opposition parties to be more specific about the nature of the allegations McDonald is facing, Sajjan said: “We will get the answers and we will get to the bottom of this,” adding that while he knows Canadians have a lot of questions, the integrity of the investigation needs to be upheld.

McDonald’s email was sent in the context of a separate ongoing investigation into McDonald’s predecessor, Jonathan Vance, who McDonald replaced just six weeks ago. 

Following his retirement, military police launched an investigation into allegations against Vance over alleged inappropriate conduct while in uniform that CTV News has not independently verified. Vance has denied wrongdoing.  

The House of Commons National Defence Committee then also began its own study into “addressing sexual misconduct issues in the Canadian Armed Forces.”

The investigations are reviving conversations about the need for external oversight of the military. 

 “I have serious difficulty in having a defence department investigating this particular thing. If the commissioner of the RCMP had been involved I don't think we would have expected the RCMP to investigate it. And when we had complaints against the governor general, we went outside government to have it investigated. So, first and foremost, I don't think the defence department should investigate itself,” said retired colonel Michel Drapeau on Thursday.

It has also prompted questions over what exactly Sajjan was aware of and when, the sufficiency of the vetting being done for some of the most senior positions within major federal institutions and why allegations serious enough to prompt these investigations were not uncovered earlier.

"When you are looking at someone that is going to have one of the highest security clearances in the entire country, that we have to do a deeper dive into their backgrounds, including all possible allegations,” said Conservative defence critic James Bezan. “They need to be setting the standard and the tone as the leader of the forces.”

It's also put new attention on the state of Operation Honour, an initiative launched under Vance’s command that is meant to combat sexual misconduct and harassment within the forces.

“Part of it is acknowledging there’s actually something to be fixed… One of the factors is that in order for people to change, culture change, there needs to be a buy in from everyone,” said former Navy reservist Marie-Claude Gagnon, who founded a group called It’s Just 700, offering supports and services for those who have experienced military sexual misconduct.  

Sajjan said that it’s “irrelevant” how it looks that both the current and former top ranking soliders are under investigation. “We don’t make decisions based on how the perception is… Our institution is far greater than any one individual,” he said. 

Lt.-Gen. Wayne Eyre has been named the acting chief of the defence staff.

With files from CTV News’ Joyce Napier and Glen McGregor