It was supposed that priests said Mass in a cave behind Connolly's house in Prizon and also in another cave on the far side of Cnoc Spulagadaún in a place called the Omar in Poll Mona.
The priest used to go in disguise from place to place administering the sacraments and saying Mass for the people.
There was a notorious Priest Hunter in his County of Mayo. He was a Seán Mullouney known as "Seán a Sagart". He killed priests as if they were wild animals and received £5 per head from Bingham governor of Mayo as his reward.
Seán Mullouney was a native of Ballintubber. He had been for a period without finding a priest. Bingham sent for him and said,

"John, you're doing badly."

John then conceived a wicked plan. He had a sister who was a good woman. He pretended that he was sick and went to her house and begged of her to let him lie on a bed. She believed that he was genuinely sick and hoping to convert him from his evil ways she admitted him. He then pretended that he was dying and repentent for his wicked deeds and asked her to send for a priest. She believed him and knowing where there was a priest she sent for him. The priest came in the fullness of his charity but alas! Seán a Sagart jumped upon him and killed him.
This poor priest had a nephew who was a priest too. Seán suspected that he might be at his Uncle's funeral and he lay in wait on the day of the murdered priest's burial. As the funeral procession passed by Seán jumped out on this young priest. The priest ran for his life, but Seán followed him. There was a pedlar named McCann at the funeral and he went in hot pursuit of the two. They were running through a plantation when the priest stumbled and fell. When the pedlar came on them Seán had just fallen on the priest. The pedlar seized the knife as Seán lifted it to stab. He plunged it into Seán's heart and then ran as fast as he could across country and offered his wares for sale at Bingham's door.
By doing so he escaped suspicion.

In those days when it was so hard to be present at Mass people who had a great devotion to the Holy Sacrifice often got a message in a dream of the place where Mass would be celebrated.
They would rise and go to the spot and actually find the priest offering Mass. It has also been said that Mass bells were heard ringing from the direction of some mountain cave where Mass was to be celebrated and those who heard the call of the bell followed the sound and had the privilege of assisting at Mass.