GAA is a huge part of life in Charlestown which nestles on the Sligo/Mayo border.
The local club, Charlestown Sarsfields, are part and parcel of life here; and Detective Garda Horkan was a vital cog in the workings of the club, as a player in his earlier years and in more recent times as a volunteer and coach.
He was a Mayo Senior Football Championship medallist with the club in 2001; and only last week had recorded a podcast with other members of that successful team to reminisce on those glory days.
"Hugely involved with the GAA club right from underage level right the way up through to senior," says Alan Crean, owner of Aston Crean in the town, a company specialising in flooring, tiling and carpet.
"He played a major part in our success in winning a county title in 2001 and he remained involved with different levels in the club ever since.
"Fundraising, stewardship, training, everything like that so he had a huge impact on our GAA club over the years.
"He'd recently completed a podcast as well only in the last number of days. The club had started creating podcasts during lockdown for a bit of entertainment and only in the last number of days he had only done one with one of the members of that county winning side." Mr Crean explained.
36 hours after the news had broken, the loss of Detective Garda Horkan was beginning to sink in for many in the area.
"I haven't seen the town at a low ebb quite like this that I can ever recall to be quite honest," Mr Crean said.
"Everybody is in utter shock really and I suppose it is because it's such a tragedy and because Colm was such an extremely popular guy, he knew everybody.
"He treated everybody the same, greeted everybody with a smile, a lovely character, a lovely man and extremely well respected no matter who you'd speak to, young or old.
"Utter shock, utter disbelief, a huge amount of deep sadness, sense of loss for such a man like Colm. Complete shock to be quite honest, nobody could quite believe what they were hearing and reading. Just such a senseless loss of life."
At the home of Charlestown GAA , Father O'Hara Park, a tricolour flew at half mast. as at the Garda Station.
Geraldine Cronley, a nearby resident, said the town will miss Detective Garda Horkan "very much".
"It's very sad and pure quiet," Ms Cronley said of the mood in the town. We'll miss him very much.
"We knew the family very well, the father was a lovely man, if you were short of a few pound he wouldn't be long giving it to you or a taxi home or anything."
Colm was a retained firefighter in the town before he joined An Garda Siochana,
He was also a Minister of the Word in St James' Church in the town where he was baptised, and received the sacraments of Holy Communion and Confirmation and where on Sunday his funeral Mass was held.
Covid-19 restrictions made the arrangement of a State Funeral more challenging - but all sectors of the community helped in any way they could.
"It's very sombre and subdued, people are just numbed really at the news," local councillor, Gerry Murray told The Sligo Champion.
"You don't expect these things to happen in our small towns in the west. Colm was raised in the square, his father had a pub across from me in the square, and he was a great man.
He knew how to handle people, he had good interpersonal skills and he was fundamentally savvy when it came to policing, he knew how to handle and manage people.
"They're in the town for generations, they've a huge circle of relations, not to mention friends and they've been in the pub business, in the taxi business, extremely well known and well respected right across east Mayo and south Sligo."