As gardai quizzed a suspect in his 20s, parish priest Fr Dominick Gillooly wondered why every doorway wasn't knocked upon in a specified area when the call came.
He said at the funeral service in St Anne's Church, Sligo: "So many people expressed disquiet and disbelief over a reported 999 call indicating a bound and tied victim in a designated area. That would surely have warranted a knock on every doorway to check about the well-being of all persons."
Fr Gillooly recalled that instead, 67-year-old Mr Gillespie was left lying for up to 48 hours in a hallway before his discovery and death later on Saturday week in Sligo General Hospital.
Gardai have admitted they received a 999 call on Thursday week indicating a male was tied up in a house with a brown gate, but with limited information they checked the wrong house.
More than 1,500 mourners heard the priest talk about Mr Gillespie suffering a violent attack and death in one of a series of murders in the past week.