Video report by ITV News Security Editor Rohit Kachroo
The two surviving British members of the ISIS terror cell dubbed "The Beatles" have been confronted by ITV News about what they know of the last moments of murdered aid worker, David Haines.
In their last TV interviews before both were taken into custody by the US, Alexanda Kotey and El Shafee Elsheikh dodged the opportunity to directly apologise for his death.
But Elsheikh did say he would "offer my sincere apology" for his role in the logistical side of the terror group.
He added he has "no problem apologising" for moving Mr Haines from location to location during his time in captivity.
Kotey, however, remains evasive when pressed by ITV News Security Editor Rohit Kachroo: "I won't forget what I've said before."
Before adding: "I find your line of questioning irritating."
ITV News travelled to Syria with Mr Haines' daughter, Bethany, trying to get some answers from the two men she believes know where her father's body lies.
Kotey and Elsheikh have been held in a Kurdish prison in northern Syria over their involvement with the terror group.
But since we quizzed them, the area has come under attack by Turkish forces and they have been taken into US custody, their whereabouts unknown.
Before the pair were quizzed, Bethany said: "They'll know, one, that I exist and, two, that I'm not letting this go - and that I will fight for justice and I will fight to find out the truth."
Kotey is first to be questioned - but he will not apologise, instead saying: "What I will say is that I regret, that I'm sad for her that that was the fate of her father.
"That's not something that I would have wished for.
"It's not something that I'm in agreement with and if there was anything that I had done which may have lead or caused some kind of distress to her or her father while he was in detention then I apologise for that."
When asked what he would say to Bethany on what happened to her father, Kotey shakes his head and answers he's already said what he wants to say and didn't want to add anything further.
"I'm the wrong person to ask. If I had information about that, then we wouldn't be sitting here having this discussion," he says.
"You can believe it or not, it's not going to change anything."
Meanwhile, Elsheikh describes himself merely as someone who dealt with "emails, logistics, moving people around".
Elsheikh says he cannot offer Bethany any answers regarding her father's remains or the circumstances surrounding his execution.
He said: "When you're driving a van, you don't do a headcount. It's not your job, your job is to drive a van."
When he is pressed about being involved in the "detention and captivity of David Haines", Elsheikh insists: "No, when you word your statement that I was involved in the detention and captivity, it would mean that I captured him and guarded him and held him.
"It's not true. I didn't do any of that.
"I had an involvement, an interaction with David Haines and others during their detention and captivity, yes."
She vowed that the pair would not get an "easy time of it" in a courtroom while she was sat there.
"It's empowering because they know that I'm not going to give up, regardless if they're in Syria or some US prison," she tells ITV News.
"I will keep fighting and pushing and pushing them and make their lives hell until they give us the answers we want."
Bethany, 22, has travelled from Scotland to Syria in the hope of getting some closure on the events that shook her world as a teenager.
She has visited the mountain area outside Raqqa - the one-time 'capital' of the caliphate - believing it is around there that the videos of beheadings of Western hostages - including her father - were filmed.
Bethany has spent hours studying the videos for clues, trying to pinpoint the execution spots.
"It would definitely be the hills with the tracks," she says, "because that's really evident in the video that there's a track going down behind the hostage and his executioner.
"It makes you want to go up and try and find him, which is something that I can't do. But to know it's somewhere round there, it does provide a bit of comfort."
As for what happens to Kotey and Elsheikh next, that's still unclear.
They could yet face trial in the US but any extradition to America - where they could face the death penalty - could be challenged in the British courts.