"We're following up on a number of leads but would like to see if there's anything else out there," Wenatchee Police Detective John Kruse told AOL News. "We're hoping the publicizing of this reward money will loosen some tongues and generate some tips that we haven't heard yet."
Mackenzie Cowell was last seen alive at about 3 p.m. on Feb. 9, when she left the Academy of Hair Design in Wenatchee, where she was a student. About seven hours later, Cowell's red 1997 Pontiac Grand Prix was found abandoned near a cattle gate in Pitcher Canyon. The location is roughly five miles south of Wenatchee, in a rural part of the county.
When sheriff's deputies arrived on the scene, they observed a single set of footprints leading away from Cowell's car. Inside, they found her purse and several articles of clothing. However, her debit card and cell phone, a maroon LG EnV2, were missing.
Using tracking dogs and a helicopter, police conducted a search for the teen over the next few days. Then, on the afternoon of Feb. 13, a person walking along the Columbia River at Crescent Bar stumbled upon Cowell's body, fully clothed. She had been strangled and stabbed in the neck, according to the autopsy results. There was no sign of sexual assault, police said.
Police won't comment on whether Cowell was murdered at the scene -- which is roughly 20 miles from where her car was found -- or transported there afterward.
A senior at Wenatchee High School, the daughter of Reid and Wendy Cowell was known for her love of dance, exercise and working with hair, according to the The Wenatchee World.
During a memorial service, the Rev. Sandy Brown read a brief statement from Reid Cowell, who called his daughter a "special gift" from God and said, "You will never leave my heart. I can't believe how much I miss you."
To catch Cowell's killer, authorities formed a task force of 20 investigators from the Douglas and Chelan counties sheriffs' departments, the Wenatchee Police Department, the East Wenatchee Police Department, the State Patrol and the FBI.
Kruse said several items collected from the teen's body and her vehicle have been sent to the crime lab, but he wouldn't comment on whether they had yielded any clues.
One thing investigators have homed in on is Cowell's cell phone records. They show that her phone was last used at about 3:40 p.m. on the day she went missing, and that the activity occurred near the Wenatchee Riverfront Park boat ramp. It consisted of two text messages between Cowell and her boyfriend of 17 months. Each message said, "Hey."
Police say it remains unclear why the teen would have been at the boat ramp or whom she might have met there.
The cell phone records also show that six calls were made from Cowell's cell phone just minutes after she left the beauty school. They were all placed to an East Wenatchee number but went unanswered. Kruse said investigators have since determined that Cowell was not known to the number's owners.
"We suspect it was probably a misdial," Kruse said, "but we have not been able to figure out for sure what number she was trying to dial."
To date, the task force has followed up on more than 430 leads and interviewed nearly 750 people. Several polygraph examinations have been administered as well, but the results have not been made public.
"I don't want to go down the road of who passed, who didn't pass and who's inconclusive," Kruse said. "We have no named persons of interest and no named suspects at this time."
However, Wenatchee Police Capt. Doug Jones said Cowell's family is not a focus of the investigation. "They have been 100 percent cooperative and a true partner in the investigation," Jones said in a press release.
Jones also said the $47,000 reward, which is being offered by the Mackenzie Cowell Benefit Trust Fund and the Wenatchee Valley Citizens Against Crime Pledges, is for information provided to the RiverCom Tip line (509-663-9911) that leads to the arrest and prosecution of the person or persons responsible for Cowell's murder.