The family of an Ottawa Valley boy who disappeared during a fishing trip more than 40 years ago watched from the shore Saturday afternoon as volunteer divers searched the lake where he was last seen.

A CBC true-crime podcast that delved into the cold case of Adrien McNaughton planned the dive at Holmes Lake after unearthing a new clue.

"None of it's easy," said Adrien's sister Shontelle McNaughton. "You want to find something but at the same time maybe you don't [because] that would mean maybe he's still out there."

Shontelle McNaughton and other family members of an Ottawa Valley boy who disappeared during a fishing trip more than 40 years ago watched from the shore as volunteer divers searched the lake where he was last seen. 0:27

Her brother was five years old when he was last seen wandering into the woods during a fishing trip with his father and three siblings at the lake west of Ottawa in 1972. Shontelle, the youngest in the family, was not there.

The serial podcast​ Someone Knows Something launched earlier this year with an in-depth look at the case — and a desire by host David Ridgen to find new information that might solve the mystery.

Belgian Malinois cadaver dogs, trained to only react to the scent of human remains, were brought to the lake — a first in the case, Ridgen said.

Four different dogs marked the same spot on the lake on four different days.

"We're following new information. It always surprises me that you can actually find new information," he said.

'Pretty terrible' visibility

Volunteer diver Shawn McKnight says visibility in the lake is poor. (CBC) "pretty terrible" visibility in the lake is hampering efforts. Shawn McKnight, a volunteer search-and-rescue diver, said the

The bottom of the lake is shallow and rocky to about 10 feet from the shore, then it drops off to a maximum depth of 30 feet with a fine silt covering the ground, he said.

"We're having a fairly difficult time searching," he said. "Once we get anywhere near (the silt) it kind of explodes and completely reduces our visibility to zero. So, we're going through large clouds of silt."

So far, all the divers have found in is muck, fishing lines and sardine cans, Ridgen said.

"Right now it's just watchful waiting. Trying to keep as calm as possible," he said.

If he's not here, then what happened? If he is here, what happened? - Shontelle McNaughton

Shontelle McNaughton said the renewed interest in the case has once again shone the spotlight on a family that prefers its privacy.

"It's outside of our comfort zone," she said, adding that it was still important to be at the lake as divers searched.

"One way or the other, the outcome creates more questions. If he's not here, then what happened? If he is here, what happened?"

One of the podcast producers said Saturday evening that the search wouldn't continue Sunday but could possibly continue at a future date.

In 2009, OPP released an age-enhanced sketch of what McNaughton might look like as a middle-aged man.

The podcast team also enlisted a forensic artist to come up with seven possibilities of what McNaughton could look like today.