Detective Garda Colm Horkan was remembered by his family as a "rock" and the "glue that held it all together".
Hundreds of gardai from Sligo, Leitrim and Roscommon divisions gathered in Charlestown, Co Mayo, to pay their respects to the detective, who was shot dead on Wednesday night in Castlerea, Co Ros- common.
His funeral took place in St James' Church, where he was baptised and made his First Communion and Confirmation.
In an emotional tribute, his brother, Brendan, said the officer was cut down in the prime of life doing the job he loved.
"He was a rock in our family, the glue that held it all together. Colm was a gem, a son and brother like no other," he said.
He described him as "kind, considerate, selfless and, above all, loyal to the core".
Mr Horkan said the journey home from the post-mortem "tugged at heartstrings" as communities lined the roads and streets.
"Mine and my family's emotions are in turmoil at this time. He was a man who made our lives so much better," he said.
"Today is such a horrible and nonsensical event. Reality hit us square in the face."
Det Gda Horkan was "a man of sheer class", which must mean "a seat for him at the top table".
"Our loss is heaven's gain. Today we say goodbye to a giant who brought joy and happiness for 49 fantastic years," he added.
Det Gda Horkan's coffin was carried up Chapel Street by his four brothers and was then taken over by members of An Garda Siochana.
Castlerea Garda Station Superintendent Goretti Sheridan announced a nationwide minute's silence from the altar at noon and Taoiseach Leo Varadkar paid his respects at Garda Headquarters in Dublin.
President Michael D Higg-ins held a vigil at Aras an Uachtarain.
Chief celebrant of the mass and parish priest Monsignor Tommy Johnston describe Det Gda Horkan as "one of nature's gentlemen".
"Colm Horkan was a good man, one of nature's gentlemen, that and more," he said.
"One of the good things that have emerged from Covid-19 is that it has helped us to recognise the importance of our frontline workers, and up there, very much to the fore, are our guards helping to keep the nation safe."
Fr Johnston included a tribute written by an unnamed friend in his homily.
"Colm was a cherished member of our community, a brother to everyone, young and old," the tribute said.
"We grew up together, played together and performed in school plays together."
Fr Johnston said the community was in deep mourning.
"We are heartbrok- en for Colm's family, coll- eagues and many, many friends," he said.
"It will take a long, long time for our community to come to terms with this senseless act of violence against our brother Colm."
The mass began with Fr Johnston saying Det Gda Horkan was "a man of goodness".
His brother Dermot spoke tearfully at the altar as gifts were brought up.
A garda notebook symbolised his service, as well as a Charlestown jersey in green and white and his car keys - he had a "great passion for cars".
A CD was brought up as the detective loved music and concerts and was "always in the queue for tickets at Ticketmaster", as well as his family photo to symbolise the "strong bond".
His "love for fashion" was symbolised by a Tommy Hilfiger shirt and his Liverpool FC tie pin, with "You'll Never Walk Alone", "summed up Colm perfectly".
Justice Minister Charlie Flanagan, as well as Garda Commissioner Drew Harris, attended the funeral.
In accordance with government guidelines, 25 family members and relatives were inside the church, which included the minister and the commissioner.
Mr Harris said Det Gda Horkan "epitomised what all of us as members of An Garda Siochana should strive to be".
"His policing service was characterised by hard work and diligence," he added.
While he said his death was a heavy blow to the force, the Roscommon and Mayo communities had come out in support.
"The outpouring of condolences and support in response to Colm's death and the shocking manner of his death has supported all of us in An Garda Siochana," he said.
"Those of us who continue to serve can honour Colm's legacy. May he rest in peace."
As he concluded, there was a round of applause from gardai standing outside the church.
A private burial took place after the mass.