EDMONTON -- An Alberta Mountie is paying tribute to his colleague who was one of 22 people killed by a gunman in Nova Scotia.

Coincidentally, Parkland RCMP Const. Stirling John had been working for months on a song about each person being the best version of themselves for their community.

"I envisioned a lighthouse as a cover of this song: people giving them light in the darkest of days," John recalled.

Then tragedy struck in the maritime province April 18, as a man disguised as an RCMP officer victimized more than two dozen people over a course of 150 kilometres.

Several people had been killed or injured already, including a police officer, by the time the shooter crossed paths with on-duty RCMP Const. Heidi Stevenson.

The gunman drove into her vehicle head-on, then shot her fatally.

Police would not know for days how many others had been murdered.  

"I just thought, man, the lyrics to this song need to be heard across the world – but especially Nova Scotia," John said, telling CTV News Edmonton he quickly got to work rewriting the piece in Const. Stevenson's honour.

In part, the song's lyrics read:

Down along your horizon / Everything gets dark / This ain’t a storm you want to be alone in / Let me be your rock / Can I be your light / Even though the endless nights / There’s nowhere I wouldn’t go / Nothing I wouldn’t do

“Const. Stevenson was the definition of a hero. She responded to the call and she gave her life," John said.

“And now we need to be there for our first responders and our people who have stepped up for this time. To be there for them.”

Despite never having met Const. Stevenson, or visited Nova Scotia, John described the RCMP as a family. In 2015, he served as part of the honour guard for killed St. Albert officer Const. David Wynn.

"We are there to back each other up. And when a member falls, we are there for them and their families.”

Now, he's sharing the message through music. A video of his performance of the piece, alongside fellow RCMP officer Matthew Fievel, has been viewed more than 50,000 times.

"I just want to tell people, we’re here for you. Lean on each other at this time and we’ll get through together.”

With a report by CTV News Edmonton's Bill Fortier