Crossan (73), a former priest of the Diocese of Raphoe, appeared at Letterkenny Circuit Court via Videolink on Wednesday, where a five-year sentence was imposed on him.
He is currently being detained in the Midlands Prison.
Crossan pleaded guilty to nine sample charges out of a total of 96 charges in relation to one victim, a boy who was aged between 10 and 15 at the time of the offences.
The court heard that the victim in this case went to cops after he heard Crossan had been convicted of sexually abusing another youngster in 2021.
The court was told that he was a regular visitor at the boy's home and that the boy first remembered something happening when he was only ten years of age.
The victim told gardaí it became regular for him to stay over and that the abuse progressed very quickly, and that he would feel embarrassed and ashamed after the sick events.He would spend most of the time in the foetal position thinking of “happier things."
The incidents became so regular that it became normalised, and he would stay over in the priest's bed hundreds of times, he said.
In the wake of the sentencing, Monsignor Kevin Gillespie reiterated an apology on behalf of the Raphoe Diocese.
In a statement Thursday morning, Msgr Gillespie said: “On behalf of the Diocese and with a deep sense of shame for his actions, I sincerely reiterate my apology to the victim.
“Conscious that the quest for justice is only one part of the journey of healing, nevertheless I hope that the vindication provided by today’s sentencing will in some way bring support and consolation to them, their family and friends.
"I encourage anyone who may have been abused, or is suspicious of any abuse, to report it to the state authorities, or the diocesan Safeguarding Office immediately.
"To report a concern or complaint of child abuse, either current or historical, please contact Margaret Northage, the Designated Liaison Person for the diocese on 086 2183 011. You are advised to also contact statutory authorities.”
In a victim impact statement, read out in court, Crossan’s victim spoke of how any sense of a normal childhood was stolen from him.
"I felt sick to my stomach. I will not let you steal another day of my life. If there is a God then there is almost definitely a hell and that is what is waiting for you."