'I Made a Terrible Mistake'

March 3, 2006 — -- The water was cold, the mystery deep. It was the summer of 1999 when scuba diver Carl Claren decided to go for a swim in a suburban Cleveland quarry near the new house he was building. As he dove along the shallow edge of the quarry, he noticed something unusual.

"There was a duffel bag, and I figured there was something in there, brought it up in the yard, unzipped it and the leg and the foot fell out," Claren told "20/20."

Inside the canvas duffel, he found rocks -- and a dead baby boy with a stab wound and a head injury, his umbilical cord tied off with a barrette.

The body of the nearly full-term baby shook the small Ohio community of Columbia Station so deeply they gave it a real funeral, a grave and a headstone bearing the name: Baby Boy Hope. Community members vowed not to rest until they knew who among them could do such a thing.

Lorraine County Sheriff's Detective Karl Yost became consumed by the mystery, developing a picture of the killer in his mind.

"I think we all wanted to think there was some kind of monster behind this, because who else would do this besides a monster?" Yost said.

But while he looked for the monster, just a few miles away was someone totally different, a 10th-grade girl, Jessica Coleman.

Jessica was a pretty, popular student-athlete with good grades -- and a terrible secret. When Jessica was a freshman, she and her boyfriend, Tom Truelson, fell in love and became sexually active.

The following fall, just as Tom was preparing for college and the two teenage lovers were worried about parting, she started to feel her body changing. She missed periods. But being just 15 and athletic, irregular cycles were not that unusual. By the fifth month, she began to worry.

She and Tom bought a pregnancy test and the results were positive. She was pregnant with his child.Jessica panicked. "I wanted it to be wrong. I thought, how can I tell my family and what are people going to think of me?" she said.

They made a decision to simply ignore the results. Perhaps, they thought, if they didn't acknowledge the situation, "it might just go away," she said.

Of course, it didn't. Still, she did her best to make sure her pregnancy went unnoticed by her family and friends. "My body actually did not change at all. I didn't gain any weight, because I had an eating disorder at the time. I wouldn't eat. I was afraid to eat, I was afraid to show, I was afraid that people would find out," she said.