KENNEWICK -- Donald Schalchlin was just 15 when he was charged with killing his own mother and sister back in December, and up until Thursday, his hearings were held in juvenile court.

But the state wants to change that.

Attorneys held a hearing to decide if Schalchlin will be tried as a juvenile or an adult, called a declination hearing.

Prosecutors called several witnesses to the stand including the lead investigator on the case, Benton County Sheriff Detective Bob Brockman.

In a matter of moments, Brockman turned the courtroom into a crime scene.

We do want to warn you, some of the details are graphic.

"Josh made a statement, something to the effect of 'I'd really like to kill someone," Brockman testified. "At which time Donald said to Josh 'we could kill my mom and sister. Josh said he asked Donald 'are you okay with that? Are you sure?' And Donald said 'yeah, that would be fine and then we could go have sex with them."

Josh is Josh tucker, the teen who pleaded guilty to Lori and Elizabeth's Schalchlin's murders in March, and who implicated Donald as an accomplice.

"We had a large amount of blood wiped off the floor," Brockman said.

Benton County Prosecutor Andy Miller fired off question after question, leading Brockman to recount the darkest moments of the case last December.

Brockman told of the details of Elizabeth and Lori Schalchlin's brutal murders, and of Donald's sentiment that night -- a boy, he said, who showed no emotion.

"Josh said that Donald reached into the butcher block and handed him one of the knives," he said. "It was a 10 inch knife with the serrated blade and prongs at the end."

In all, detectives said Tucker used a serrated knife, a steak knife and a meat cleaver to kill the women.

"Josh said Donald had a big grin on his face and (Josh) reached around and cut Elizabeth's throat," he said.

Tucker killed Elizabeth first, slitting her throat in one single motion.

"At which point, Donald told Josh, I can't kill anybody but I can help you kill. I can help you kill others," Brockman stated.

From there, Tucker attacked Lori. The murder was so brutal, Tucker broke the knife used to stab Lori. The detective said it was Donald who grabbed a dumbbell to finish the job. Lori's desperate 911 call told of the horror.

"she was yelling 'help me, help me.' It was a voice full of terror and fear."

When the phone went dead, dispatch called back. Donald answered.

"the second caller was a voice of no emotion. Flat," Brockman said.

Donald's attorney illustrated a different picture: a young boy confused and scared for his family. Donald told investigators he was trapped and couldn't help his own family because Tucker would hurt him. Donald told investigators he tried calling 911 for help but Tucker made him hang up.

Prosecutors expect the judge to make a decision tomorrow on whether Donald will face charges as an adult, the same way Tucker did. Tucker is serving a life sentence.