Bob Geldof failed to stop his late daughter Peaches from "running away" from rehab.
The 25-year-old star died from a heroin overdose in April 2014 and the Boomtown Rats frontman has revealed she sought help to overcome her addiction and while she was initially "doing well" at a clinic in the US, she eventually walked out of treatment.
Asked if he was aware of her problems, he said: "If you're talking about drugs trouble, I knew she was doing drugs.
"I wasn't specifically aware. I knew that she'd always dabbled and that the panic was always there.
"By 2013 we'd been through it. The family had gone to Utah to a rehab place there. She was doing pretty well and we all flew out, because you have to.
"Then she ran away from there. I tried to stop her at the door but there's nothing you can do. She was free to leave."
The 68-year-old rocker - who is also father to 37-year-old Fifi and Pixie, 29, from his marriage to Paula Yates and raised his late ex-wife's daughter Tiger Lily, 23, following the deaths of both her mother and father Michael Hutchence - loves to help his widowed son-in-law Thomas Cohen with Peaches' two sons, Astala, seven, and six-year-old Phaedra.
He said: "They're beyond stupidly cute and completely hilarious. And of course, they're guys. I've only had girls, so that's a big change. Lifting them up, I can't believe the weight. Tom just scoops the two of them up. Some strength, he's got."
Bob remembered Peaches as always being a "frantic" child with a "constant panic" in her eyes.
He told Event magazine: "She was lovely. But she was always a frantic child as a little baby. She couldn't sleep. And that continued all through her infancy.
"She did weird little things as a kid, she had these cute habits. She'd go around collecting twigs. And she sucked a dummy until she was ten or 11. She'd go around truffling on her dummy and topping up her twig collection.
"She was such a clever, sweet, eccentric girl. There was always that franticness, that constant panic in the eyes. You know the great Leonard Cohen song, Famous Blue Raincoat? 'Thanks for the trouble you took from her eyes, I thought it was there for good, so I never tried.'
"Well, I did try. Of course, I did."