Eric Clapton's song "Tears in Heaven" captures the grief and heartbreak the singer-songwriter suffered after the loss of his 4½-year-old son, Conor.
Now, 15 years later, Clapton's former girlfriend and Conor's mother is sharing never-before-seen video of the child who inspired the song.
Watch the full interview on "20/20" Friday night at 10.
Conor was just 4½ when he fell 53 stories from an open window. He was living with his mother in New York City.
"He went in this room, opened the door," said his mother, Lory Del Santo. "As soon as I entered the room and I see the window. Where can he be?"
For the first time, Del Santo talked extensively on camera about the heartbreaking events of that day to international interviewer Daphne Barak.
Del Santo also provided ABC News with exclusive access to her private videos of her son.
The couple met in 1985 while Clapton, then 40 and already a guitar legend, was on tour in Italy.
Del Santo, a young actress and model from Verona, said they decided to start a family during their first weekend together.
Conor was born the next year.
"He was an angel, I think. Really, he was," she said. "He was beautiful, I think."
Del Santo, a photographer, documented Conor's life from the beginning. After his death, she locked the tapes away because they were too painful to look at again.
Fifteen years later, the videos show a happy child: Conor growing up as a toddler, emulating his famous father.
He loved listening to Clapton's music and had dreams of being like the famed "slow hand."
"I understand every kid wants to do what the father does, but in this particular case, he really wanted it very badly," Del Santo said.
Although the couple were no longer together, Clapton and Del Santo shared their child's profoundly tragic death.
Clapton told Barak in 2003 he was able to work through his grief with music.
"I almost subconsciously used music for myself as a healing agent, and lo and behold, it worked," Clapton said. "I have got a great deal of happiness and a great deal of healing from music."
Although Conor's life was short, his death created a greater public awareness for children's safety.
"Use guards on windows and safety gates on stairs. It's easy, and it could prevent a terrible tragedy. Believe me, I know," Clapton said in a public service announcement.
Clapton and Del Santo traveled to England to bury their son.
Just days before Conor's death, Del Santo helped him with a letter to his father.
"And he said to me, 'What should I write?' And I said, 'Well, write I love you, Dad.' And he wrote that," Del Santo said.
"So, when we arrived in London, he receives the mail -- this was after the funeral -- and he, and I, was actually there. And, he opened up, and it was this letter," she said. "That moment I cannot forget forever."