KENNEWICK -- Benton County sheriff's Detective Scott Runge studied strings he taped on a wall near a mock blood-covered crime scene and tried to figure out what happened.

The strings were used to mark the angle of impact based on the blood spatter. They were then measured to show how far away from the wall the victim was when he was struck.

"My guess is it's going to be two separate events," Runge said Friday as another officer measured blood spatter on a second wall.

Runge speculated that a knife was used in the assault, but then said he thought the victim was beaten to death because there would be more blood if a knife was used.

After simulating the motions of how the attack could have happened, he went back and sided with his father, Kennewick police Detective Rick Runge.

"You're right," he said. "It's probably a knife."

The two detectives were investigating a mock crime scene using the skills they learned during a weeklong class on blood spatter to figure out what happened.

Blood at a crime scene can tell a story and fill in the blanks from witnesses or suspects, said Dan Christman, a Bothell police officer who taught the class.

The way it drops. The way it smears. The way it sprays onto a wall.

"If we ignore blood evidence at a crime scene, we're just ignoring a huge chunk of information," Christman said. "This blood stain evidence tells a story."

Christman, who has been with Bothell police for 14 years and had 15 years with the Snohomish County Medical Examiner's Office, spent a week at the Kennewick police station teaching a group of 20 law enforcement officers about blood spatter.

Detectives in the class were from the Richland, Kennewick, Pasco and Yakima police departments and Benton County Sheriff's Office. There also was a prosecutor from the Netherlands who attended as an international student.

The class cost $399 a person, but the Tri-City Fraternal Order of Police covered the tuition and Kennewick police provided the training space, Christman said.

In addition to a classroom lecture that included pictures and information from actual crime scenes, investigators conducted experiments to see how blood drips, smears and can be transferred from a sleeve to a wall.

They also studied fingerprint impressions, dropped items covered in blood to watch how the blood spattered and even had to brush up on their trigonometry skills.

On Friday, the investigators used the skills they learned during the week to investigate five mock crime scenes to see if they could figure out what happened based on the blood spatter in the room.

Cow's blood was use to create the mock scenes, Christman said.

Scott Runge worked on a team with Rick Runge; Mary Sellars, Kennewick police's evidence technician; and Petra Gruppelaar, a prosecutor with the Dutch Public Prosecutor's Office.

The limited information they received about the crime scene was that a father and son lived in an apartment together, they both drank a lot, the father was found dead in the corner of a room and the son was gone.

"And now we have to figure out what happened," Gruppelaar said.

After measuring the blood spatter angles, Gruppelaar speculated that the father suffered a blow to the head. She thought the handprint on the ground was left by the father after he touched his wound.

Rick Runge, however, thought the handprint belonged to the son and was left as he crouched over his father during the attack.

"I think it was a knife because of the size of the cast off," he said.

One thing that stumped the team was a handprint and blood smear on the wall. They thought the print was left by the son as he stood up and the smear was from the son dragging his hand along the wall as he ran out of the room.

They presented their theories to Christman, who explained that the father had a stab wound to his chest, a defensive wound across his right palm and multiple stab wounds to his neck.

They then learned that the handprint and smear on the wall were caused by the father as he fell to the ground. The blood smeared to the right, which indicated he was coming down, Christman explained.

"Now I can look (at) it and say we have four events (that occurred based on the blood spatter)," Scott Runge said. "It paints, literally, a picture."

Rick Runge said he's never analyzed blood spatter in detail at a crime scene.

"What's fun about it is it makes you stop and think," the Kennewick police detective said. "Knowing how to do it sure does tell a lot better story."

Police agencies in the Tri-Cities often call on the Washington State Patrol Crime Response Team to process scenes at homicides. But Christman said detectives can use the skills they learned this week, even if they are not the ones taking the detailed measurements.

"There's a level of immediate gratification with blood spatter," he said. "You can walk into a room ... without even measuring (the spatter) and walk way with some knowledge of what happened."