Murder victim Katherine Waring was tortured with an electric stun gun, hit on the head with a wine bottle and dropped in a bathtub following a ruse to see if the athletic 28-year-old could fit into a suitcase.

Those details, describing Waring's last moments, were disclosed Friday in court, where one of her accused killers pleaded guilty to manslaughter, obstructing justice and forgery.

As part of her plea agreement, defendant Heather Kamp must continue to cooperate with authorities, including testifying truthfully at the upcoming trial of Ethan Mack, who prosecutors believe is responsible for Waring's death.

Kamp, 31, of James Island spoke in a whispered tone inside the Charleston County Judicial Center as she admitted to participating in killing Waring on the night of June 12-13, 2009, just hours after she, Waring and Mack, 30, went out for dinner.

At the hearing, 9th Circuit Solicitor Scarlett Wilson gave the first public account of what authorities believe happened that night after the three dined at Wasabi restaurant in downtown Charleston, setting in motion what she called Mack's long-stewing desire to kill Waring.

According to the prosecutor, tensions had risen between Waring, Kamp and Mack in the days and weeks before. Prior to that time, Waring had befriended Kamp and introduced her to Mack, and he and Kamp became intimately involved. When Mack and Kamp were indicted in February, Wilson said the motive in the case was financial gain but that "other threads" played a role, including jealousy on Kamp's part.

On June 12, Kamp made plans to eat with Waring, and Mack decided to join in. "Mack made insinuations that he may try to kill Ms. Waring that night," Wilson told Circuit Judge J.C. Nicholson Jr.

After the meal, the three went back to the Riley Road apartment Mack and Kamp shared, to party. "At this point, Ms. Waring was intoxicated," Wilson said.

As the evening wore on, Mack allegedly asked Waring to play a game to see if she could fit into a suitcase. The game included betting on whether Waring could do it.

"Ms. Waring was laughing and joining in the fun, as she tended to be athletic and enjoy the challenge," Wilson said. She added later that Waring didn't realize "the danger she was in."

While Waring was in the suitcase, Mack brought out a stun gun, Wilson said. "At first," she said, "Ms. Waring was annoyed and thought he was playing."

Mack began jolting Waring repeatedly, causing her to struggle and leading Mack to strike her in the head with a wine bottle, Wilson said.

Mack then directed Kamp to hold the suitcase lid down while Waring reportedly lost consciousness. Kamp, acting on Mack's orders, filled a bathtub with water, while Mack pulled the suitcase with Waring inside into the bathroom.

"With some initial help from Kamp, Mack put Ms. Waring in the tub," Wilson said. "Although unconscious, Ms. Waring was still alive."

The next day, the pair dumped Waring's body in a remote gated community on Wadmalaw Island, prosecutors allege. Her remains were found four months later on Oct. 10 after Kamp led investigators working for Waring's family to the site. No definitive cause of death was made.

Under the plea agreement, Kamp faces a total of 45 years behind bars -- 30 for voluntary manslaughter, 10 for obstruction of justice and five for forgery connected to cashing Waring's checks. But prosecutors can seek a reduction of that time if she remains truthful and cooperative during the course of the investigation and trial. Mack's trial is set for the week of Oct. 4, Wilson said.

Kamp said little in court other than acknowledge Nicholson's questions and to confirm her record. She is the mother of four children, attended two years of college in California and was briefly married.

A third suspect, Terry Keith Williams, 32, of James Island, also was arrested on obstruction charges. A police affidavit accuses Williams of helping to move Waring's body and lying to police about how he ended up with her iPod.

Waring's father, Tom Waring, attended the hearing Friday but opted not to address the court.