Mackenzie Cowell

In December, the Cowell task force made a second arrest. Wilson's friend Tessa M. Schuyleman was accused of—but never charged with—helping Wilson to conceal the crime. She was instead charged with obstruction of justice for an unrelated case. Detectives claimed that many photos were found on Wilson's computer of Schuyleman "posing as a dead person" on the spot in Wilson's apartment where Cowell's blood was found. Schuyleman claims she had no knowledge of the blood stain and that Wilson had told her to pose there.

After an extensive investigation, police implicated 29-year-old Christopher Scott Wilson – a beauty school classmate of Cowell's – in her death. Police began to suspect Wilson after several people came forward claiming that he had a fascination with death and serial killers. Wilson was arrested after DNA evidence linked him to the crime scene. Police later found Cowell's blood in his apartment.

Prosecutors upgraded Wilson's charge from second-degree to first-degree murder in April 2011, stating that his actions constituted premeditation. If convicted, he would face a sentence of 20 to 26 years in prison. Before the trial began, Wilson rejected a plea deal in which he would have received a prison sentence of about six and a half years in exchange for pleading guilty to first-degree manslaughter.

Cowell went missing shortly after 3:00  p.m. on February 9, 2010. She was last seen on surveillance video leaving the Academy of Hair Design, walking to her car and driving away. She had told classmates that she would be back in less than 15 minutes. Around this time, she sent a text message to her boyfriend that said, "Hey, what's up". This was the last time she is known to have used her phone.

The investigation was headed by the Mackenzie Cowell Task Force, a multi-agency police group assembled after the recovery of Cowell's body. The task force included law enforcement agents from the cities of Wenatchee and East Wenatchee, and from the counties of Chelan and Douglas. An FBI agent and two officials from U.S. Immigration and Customs Enforcement also assisted the task force. The case was the largest multi-agency investigation in the Wenatchee area since an attempted serial bombing in 1997. Police interviewed over 800 people throughout the course of the investigation.

Mackenzie Nicole Cowell (April 1, 1992 – February 9, 2010) was a 17-year-old American youth who went missing and was murdered in February 2010. She was last seen at the beauty school she attended in Wenatchee, Washington. Her body was discovered on the banks of the Columbia River four days later on February 13, 2010. A post-mortem examination determined she had been strangled, stabbed in the neck, and had suffered blunt force trauma to the head.