Clothier, they say, fell victim to drugged-out acquaintances, who forcibly injected her with some sort of controlled substance.
When the injection killed her, the attackers stuffed Clothier's body in a laundry bag, tying it around her neck and using her yellow turtleneck sweater to cover her head.
Then they left her body in a secluded section of the twisting creek. She lay partially submerged, undetected, for nearly five weeks until the fishermen found her.
Bucks County District Attorney David W. Heckler and Northampton Township Police Chief M. Barry Pilla Jr. revealed the answer to the mystery during a news conference at the police headquarters office yesterday morning.
A 2005 tip from a woman who said she believed she'd owned the laundry bag relaunched the investigation.
The three men involved in Clothier's death are now dead themselves. Police refused to identify them yesterday.
"If any of those men had been alive when police received this information, even if they were clinging to life support in a nursing home, instead of standing before you today, we would be working to gather evidence with which to achieve a murder conviction," Heckler said.
"However, these men are dead and beyond the reach of human justice. Since we cannot charge and prosecute them, they will never have the opportunity to defend themselves, and it accordingly would be wrong to disclose their names."
Still, authorities celebrated the sleuthing that led to the killers' identification, saying that solving the case gives closure to Clothier's lone survivor - her older sister - and the hundreds of law-enforcement officers who tried to find her killers.
Clothier's sister, Susan, would not comment, police said. But others who remember the case eagerly expressed their relief.
