Elliot Turner, 21, has won the right to appeal his conviction and sentence, after he was sentenced to life in prison with a 16-year non-parole period for strangling Emily Longley, 17, in Bournemouth, England, last year.
A date for the appeal is yet to be set.
Turner will receive a full appeal hearing before three judges at the Court of Appeal in London, the Daily Echo reported.
Emily's body was found in Turner's parents' Bournemouth home on May 7 last year.
Her father, Mark, said the family were told about the appeal by British police on Saturday.
"We were gutted. But at the same time it was not out of the blue. We obviously knew that he was going to appeal and we were hoping that it wouldn't get any further than that, so to find out it had got to the next stage it was a blow.
"It just extends the process. It's almost becoming a never-ending process now.
"It's not great timing, just before Christmas, which is going to be tough enough anyway."
Mr Longley said he has few details about the basis of the appeal. It is understood it may hinge on covert evidence used in the trial.
"I don't know too much about it. The police told me that they didn't have many details. I'm just waiting to hear really ... I'm a bit in the dark, I'm afraid."
He was, however, confident Turner would lose the appeal.
"The case is robust and I do know the police are confident," Mr Longley said.
"We're still confident and still have faith in the police. They've delivered many, many times. If they're confident then we're still confident."
During his trial, the court heart that Turner had "bullied, harassed, threatened and assaulted "Longley during their relationship, before going "absolutely nuts"in a jealous rage on the night he killed her.
Turner's parents Leigh, 54, and Anita, 51, were jailed for 27 months in July for perverting the course of justice, after they destroyed a confession letter from their son and took evidence from the murder scene.
Mr Longley said the family just want to put Turner behind them and move on.
"I don't want to have to be thinking about him and talking about him. It has been nice to have a break from that, it's just a shame that he comes back into the forefront once again. But that's the way it is unfortunately with the legal system."
The family have given up hope of an apology from Turner or any sign of remorse from the 21-year-old.
"That was one of the big things that affected us during the trial," Mr Longley said. "The lack of remorse that him and his family showed was quite staggering. It was very unexpected, I did think there would be some remorse.
"But now we're used to it, they will continue to try to worm their way out of this. I'm sure he will always maintain his innocence and I doubt we will ever get an apology, but we've just kind of gotten used to that now.
"It would be very nice for them to say, 'we're sorry we did it, we'll do our time', but that is just not going to happen with those people.
"He's certainly murdered a girl and his two parents tried to cover it up - I don't know what their reasoning is for anything. I don't think they're normal people."
