Waterloo Region’s oldest missing person case dates back to January 1978, when John McNichol left a note behind, closed up his business and said goodbye to a friend before disappearing without a trace.

Paul Heldman – the friend in question – remembers that Friday night all too well.

The pair had finished their evening shifts at the Grandma Lee’s bakery and sandwich shop in downtown Kitchener, which McNichol owned.

With the store cleaned up and bank deposit ready to go, Heldman and McNichol walked to the corner of King and Water streets, where they went their separate ways to their vehicles.

Before they parted, they said they’d see each other again on Sunday.

That didn’t happen.

While at the bakery, wondering where McNichol was, Heldman found an envelope McNichol had likely left behind on the Friday night.

Inside the envelope was a note written on a brown paper towel.

Worried about what had happened to his friend, Heldman immediately phoned McNichol’s wife Jennifer, telling her to come down to the shop.

The note said, essentially, “I’m sorry – I’ve gotta go,” Heldman recalls.

It seemed odd to him, especially considering McNichol was a family man with two young children.

“As far as I’m concerned, he was a great guy. I had a lot of good times with John,” Heldman tells CTV News.

It’s known that McNichol was in financial difficulty – Heldman says the Grandma Lee’s franchise wasn’t as profitable as he had expected – but other than that, there were few clues as to what could have happened to the 30-year-old, or why.

“John’s case is very, very difficult,” says Waterloo Regional Police Sgt. Richard Dorling.

Over the last few months, police have reopened their investigation into McNichol’s disappearance – hoping modern techniques will help them bring closure to his friends and family.

Those techniques including re-interviewing witnesses from the first investigation, and speaking to others – including Heldman, believed to be the last person to see McNichol before he disappeared – for the first time.

Complicating factors is the age of the case.

Dental records, generally the easiest way for police to positively identify human remains, have long since been destroyed.

Witnesses and others police spoke to in 1978 may not remember events as clearly as they did, Dorling says – and that also goes for the police they were speaking to.

“Most of the officers involved in this investigation have long retired,” he says.

“Peoples’ memories change, and information is lost.”

With 36 years separating McNichol’s disappearance from the present, and no sign of what happened to him, police say they’re working with a number of possibilities.

Foul play is one of those possibilities – although police say they have yet to find any evidence of that – as is suicide, as is looking for a way out of his financial predicament.

The only thing police are sure of is that McNichol wasn’t looking to escape from his wife and two young children.

“He didn’t just pack up and leave, and not contact his family ever again,” says Dorling.

CTV’s Nicole Lampa is investigating some of Waterloo Region’s cold cases this week on CTV News.