Lyle and Marie McCann's granddaughter says her family believes they are one step closer to finding them.

Nicole Walshe says her father, Bret McCann, received a phone call from the RCMP regarding Travis Edward Vader's arrest, while he was sleeping.

"He got a phone call at two in the morning," said Walshe. "[RCMP] just saying they had Vader in custody in Edson detachment."

The McCann's say the RCMP are keeping them in the loop, however they still don't know what information RCMP have on Vader that made them so interested in the first place.

""We haven't been told anything," said Walshe. "We're just thinking this is one step closer to finding grandma and grandpa. He may know something we don't know."

Although Vader is in custody, Walshe says it's important the public still stays involved in her grandparents' disappearance. A Facebook page created by the family has more than 28,000 signatures, with many offering to distribute posters.

"If they see the SUV, or the motor home, or Vader or grandma and grandpa's photo; photos of any of those things, it might trigger something in their memory." Walshe said. "So it's still relevant."

The 31-year-old granddaughter says while it may seem silly, she is more optimistic that they will find her grandparents; this, despite the fact no one has heard from Lyle and Marie since they left on vacation July 3rd.

"Every fibre of my being feels 100% that we will find them and they will be okay," said Walshe. "I honestly truly believe that."

With files from CTV's Susan Amerongen