A forensics team is carefully examining an undisclosed area west of Edmonton, where police found a missing couple's SUV. But investigators are not divulging the exact location because it's a "potential crime scene."

Lyle and Marie McCann, aged 78 and 77, vanished during a road trip to the Rockies earlier this month. Surveillance video from July 3 showed the husband refueling their motor home at a gas station in St. Albert, a suburb of Edmonton.

Two days later, their RV was found completely destroyed by a fire near Edson, Alta., a two-hour drive west of Edmonton. Their Hyundai Tucson SUV, which had been attached to the back of the RV, was not located until Friday.

RCMP Assistant Commissioner Peter Hourihan said police "suspect foul play … we assume the worst and hope for the best."

Investigators are now searching for a "person of interest," 38-year-old Travis Edward Vader.

"Mr. Vader should be considered dangerous," Hourihan said Friday. "Any sightings of him should be reported to police immediately and he should not be approached."

Vader has no fixed address.

As police search for Vader, they face heavy criticism for taking several days to start their investigation -- even after they found the burned-out shell of the McCann's large RV.

While the RV was discovered on July 5, along with its charred registration papers that showed the McCann's home address, police officially started looking for the couple on July 8 when worried relatives contacted them.

Retired RCMP Insp. Bill Majcher said it shows "a lack of investigative know-how" and is embarrassing for the police force.

"It's probably a combination of laziness, incompetence -- you can pick a lot of adjectives, but it's pretty unforgivable to have a high-value motor home found burned to the ground and do a bare-minimum of follow-up," he told CTV News Channel on Saturday.

He also said a quick check of the vehicle's registration would likely have revealed the ages of the couple.

Hourihan said one officer involved in the botched investigation has been placed on "administrative duties."