Jozef Puska has been found guilty of murdering schoolteacher Ashling Murphy in Tullamore, Co Offaly.
Ms Murphy, 23, was killed while exercising on a canal path in Tullamore, Co Offaly, on the afternoon of January 12 last year.
Puska, 33, of Lynally Grove in Mucklagh, Tullamore, had pleaded not guilty to her murder.
The jury, made up of nine men and three women, reached their unanimous verdict at the Central Criminal Court in Dublin after beginning deliberations on Wednesday.
How their child was taken away, to consider what happened here is enough to make you physically ill
Members of the Murphy family cried as they hugged each other following the verdict.
Puska briefly placed his head in his hands before staring at the floor.
Judge Mr Justice Tony Hunt told the jury: “We have evil in this room”.
Justice Hunt said: “There will be a day of reckoning for Puska.”
The judge said the case dealing with Ms Murphy’s killing was particularly difficult given “the kind of person that she obviously was”.
He said primary school teachers loved children and her GAA top showed her love of sport.
Justice Hunt told the court that to lose a child was “unnatural”.
Speaking of the Murphy family, he said: “Their position is unenviable. How their child was taken away, to consider what happened here is enough to make you physically ill.”
He said he hoped they would provide a victim-impact statement.
During the trial, the court heard that Ms Murphy had been stabbed eleven times and her neck had been slashed in a twelfth wound.
The court heard that while Puska was in hospital in the days after the murder, he told investigating gardai that he had killed Ms Murphy.
The convicted murderer later said he did not recall making the statement and told gardai he did not “know anything” about the murder while being interviewed after his arrest.
Puska, who admitted lying to gardai on multiple occasions, had told the court that he had tried to help Ms Murphy after they were both attacked by a masked man.
It was prosecuting barrister Anne-Marie Lawlor’s case that there was no other man involved in the killing.
The court heard how a profile of DNA taken from underneath the fingernails of Ms Murphy had matched that of a sample taken from Puska.
The jury also heard evidence from a woman who had been jogging along the canal on January 12, 2022.
She told the court she had seen saw a man in a hedgerow who seemed to be crouched over a person who was kicking out “like she was crying out for help”.
Justice Hunt thanked the jurors for their service and exempted them from further duty for 20 years.
He said the prompt verdict reflected that it was a straightforward case.
He said he agreed with the verdict and was satisfied it was correct.
However, he said there was no doubt the case was “difficult and upsetting”.
Justice Hunt told the jury that everyone was entitled to put forward a defence.
“You can’t make bricks without straw and what [defence barrister Michael] Bowman had in his hands was very poor stuff indeed.”
The jurors were applauded as they exited the chamber as Ms Murphy’s mother held up a framed photograph of her daughter.
The judge said he had asked for silence but said the applause was “understandable”.
Sentencing and the reading of any victim impact statement was scheduled for November 17.