CHICAGO (CBS) — A Bolingbrook girl was 13 years old when she disappeared almost 17 years ago.

This Saturday, Rachel Mellon would be 30 years old – and her father is trying to deal with her loss and the passage of so much time.

“I remember back vividly the day she was born as being the happiest day of my life, by far,” said Rachel’s father, Jeff Skemp.

“I’ve accepted the fact that she’s probably dead, and I’m just trying to move on.”

LISTEN: WBBM Newsradio’s Steve Miller Reports

But even though he believes Rachel is probably not alive and is not turning 30 this Saturday, he still cringes at the prospect of confirming that.

“It’s like when they find bones, I just go nuts until I find out they’re not hers, you know?”

Skemp believes Rachel’s stepfather, who was home alone with her the day she disappeared, is responsible.

“To me, he’s the primary number-one suspect.”

WBBM Newsradio has not been able to reach Rachel’s mother or the stepfather.

Skemp settles for reminders of Rachel. Like when he hears a song by Alanis Morissette from “Jagged Little Pill.”

“That was in her CD player when she disappeared,” he said. “I went in her room and her Walkman was hanging on the bed, and I put it on and that album was blasting.”

“Last time I talked to her on the phone at Christmas that year, she said, ‘Dad, I graduated from pop music to alternative rock and roll.’

“And I said, ‘My baby’s growing up.’ “