Rod and Jennifer O'Brien are speaking out about how they have had to re-imagine their family after the loss of their five-year-old son.

Nathan O'Brien and his grandparents Alvin and Kathy Liknes disappeared in late June. Police and the public searched for them for weeks, but police announced July 15 they had laid three murder charges against Douglas Garland.

"We've been treading water in a tsunami, we're now just crawling back on that beach and looking behind us.... We have to figure things out here and put this family back together," said Rod O'Brien.

'We just had to accept the reality that they weren't going to come home.' - Rod O'Brien

CBC News earlier learned there were soured business dealings between Garland and Alvin Liknes, including a patent dispute.

Garland, whose sister is in a common-law relationship with Alvin Liknes’s son, was arrested on July 14 following an extensive search of a property north of Calgary that is owned by Garland's parents.

"We were in a fog," said Rod O'Brien, "It's a parent's worst nightmare. And we still had hope then, but as events have developed over the summer and through July we just had to accept the reality that they weren't going to come home."

Finding a new purpose

The parents said they were initially paralyzed by grief and unable to imagine life without their son.

Today they find new purpose with the announcement of the Nathan O'Brien Children's Foundation.

It's a private charity that's been endowed with a $1-million gift from an anonymous donor in the United States.

The foundation will begin granting money immediately to children's charities in the Calgary area.

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Rod and Jennifer O'Brien see it as an opportunity to keep their son's legacy alive. 

"We actually get to do an exchange from grief to hope from here on in for ever and ever," said Rod O'Brien. "We get to work with Nathan's spirit and Nathan's name to help the less fortunate as a family."

Nathan O'Brien

Friends and family of Nathan O'Brien held a private memorial for the five-year-old in September. (Calgary Police Service)

"It's given us purpose again, helped us get up in the morning," said Jennifer. "It's been huge for us."

Besides new purpose through the foundation, Rod and Jennifer O'Brien said the countrywide outpouring of support helped get them through the darkest days.

"We would love to give them hugs and just tell them thank you to each and everyone out there because they were searching for our family during the most difficult time," said Rod.

"We're going to be OK," he said. "We're just moving forward with a new family."

Loss of parents and grandparents

While the couple have both had to learn to live without their son, Jennifer O'Brien is also grieving the loss of her parents.

Kathryn and Alvin Liknes

Kathy and Alvin Liknes were remembered at a memorial service on Sept. 27. (Facebook)

"My mom was my best friend, so when you look at who you want around you in times like this, and who you want to stand by you, it would no doubt be her."

Jennifer O'Brien said she believes her parents would have done everything in their power to protect Nathan and she takes comfort that they're all together now.