CHAPTER SIXTEEN
Kari stood in the parking lot of Southwest Running Company, watching through the storefront window as a group of runners gathered for what the sign advertised as a "Tuesday Night Trail Run.
" The late afternoon sun painted the asphalt in shades of amber, and the temperature was finally dropping below triple digits—perfect conditions for the kind of training that would kill most people but only energized the ultra-marathon crowd.
The store's door chimed as Kari entered, and conversation among the assembled runners faltered.
She recognized the look—wary recognition mixed with the kind of discomfort people got around law enforcement when death was involved.
Three of their own had been murdered in the past two weeks.
Nobody here was eager to be next on Kari's interview list, but nobody wanted to be unhelpful either.
Not when a serial killer might be watching.
"Detective Blackhorse?" A woman in her early forties approached, extending her hand. She had the lean build of someone who burned calories faster than she could consume them, all sinew and sun-weathered skin. "I'm Rachel Chase. We spoke on the phone."
"Thanks for arranging this." Kari shook her hand, noting the calluses from years of gripping trekking poles. "I know your group has been through a lot."
"We're all pretty spooked," Rachel admitted. "Half the people who usually show up for group runs have dropped out. The other half are afraid to train alone." She gestured toward the assembled runners. "Nobody wants to talk about it, but nobody can stop talking about it either."
Kari scanned the faces in the group—twelve runners in various stages of stretching and checking their gear.
"I'm trying to understand what all three victims had in common beyond the Sonoran 100.
The more I learn about how they prepared, the better chance I have of figuring out who might have targeted them. "
"Jordan Rodriguez trained with us sometimes," a younger man offered. He had a runner's number pinned to his shirt—483. "He was always asking the veterans for advice about heat management. He'd grown up running in cooler climates and was worried about the desert conditions."
"Did anyone in particular give him advice?"
The runners exchanged glances. Rachel spoke carefully. "Dr. Mendez treated a lot of us. Sports medicine, hydration protocols, that kind of thing. Jordan mentioned she'd been really helpful with his training plan."
The name registered immediately. Maria Santos had mentioned Dr. Alicia Mendez during their last call—a sports medicine physician whose name kept appearing in connection with elite ultra-marathon runners. "Did Dr. Mendez treat Jennifer Hayes or Jessica Ramirez?"
More exchanged glances. A woman in her fifties nodded slowly. "Jessica saw Dr. Mendez regularly. I know because we compared notes after appointments. Dr. Mendez had this whole theory about pushing through dehydration thresholds to build better heat adaptation."
Kari nodded, interested. "What kind of theory?"
"Controversial stuff," Rachel said. "Most sports medicine doctors recommend careful hydration management, but Dr. Mendez advocates for what she calls 'controlled dehydration training.
' The idea is that if you can teach your body to function at lower hydration levels, you'll have a competitive advantage in ultra-endurance events. "
"Sounds dangerous."
"It is dangerous," the woman in her fifties said firmly.
"I tried some of her protocols last year and ended up in the ER with heat exhaustion.
But for runners chasing podium finishes, the potential advantage is tempting.
Especially for events like the Sonoran 100, where managing water weight can mean the difference between finishing and dropping out. "
Kari pulled out her notebook. "Do any of you know if Dr. Mendez was conducting formal research? Clinical trials, that kind of thing?"
"She tried to recruit me for a study," the young man with the number pinned to his shirt said.
"Something about measuring cognitive function under extreme dehydration.
I declined because the consent forms made it sound pretty intense—like, they'd have us running in heat chambers while restricting fluid intake. "
"Did Jordan Rodriguez or Jessica Ramirez participate in that study?"
Nobody seemed certain. Rachel pulled out her phone and scrolled through messages.
"Jessica mentioned something about participating in research.
Let me see if I can find the text." She squinted at her screen.
"Here. From three weeks ago. She said she'd signed up for a performance study with Dr. Mendez and was excited about the potential benefits for her Sonoran 100 prep. "
Kari took down the information, then asked for Dr. Mendez's contact details and the location of her practice.
The runners were happy to provide both, along with a litany of opinions about Mendez's controversial methods.
Some praised her innovative approach to sports science.
Others considered her reckless, more interested in publishing groundbreaking research than protecting her patients' safety.
By the time Kari left the store, the runners were heading out for their group run—safety in numbers, nobody willing to train alone.
She sat in her vehicle and pulled up Dr. Alicia Mendez's website on her phone.
The physician had an impressive resume: degrees from Stanford and Johns Hopkins, fellowships in sports medicine and exercise physiology, published papers in peer-reviewed journals.
Kari clicked through to Mendez's recent publications.
Most were technical articles about lactate thresholds and VO2 max optimization, the kind of dense scientific writing that required a medical degree to parse.
But two papers caught her attention: "Adaptive Responses to Controlled Dehydration in Elite Athletes" and "Cognitive Resilience Under Extreme Physiological Stress. "
The abstracts described studies where participants were subjected to progressively intense dehydration while performing endurance activities.
The research claimed to demonstrate that athletes could be trained to maintain performance at hydration levels previously considered dangerous.
The papers acknowledged the risks but argued the potential benefits justified careful experimentation.
Kari dialed Maria Santos.
"Tell me you've got something," Maria answered. "Because I've been chasing my tail with Dalton's alibi for the Rodriguez murder, and so far everything checks out."
"Dr. Alicia Mendez. Sports medicine physician. How much do you know about her?"
"The name's come up. She treats half the ultra-marathon community in Phoenix. Why?"
"She's been conducting controversial research on extreme dehydration. All three victims were connected to her—either as patients or research subjects. And her methods involve pushing athletes to hydration levels that sound a lot like what killed our runners."
Maria was quiet for a moment. "You think she's experimenting on people? Using actual races as her test conditions?"
"It looks like that's a possibility." Kari started her engine. "Can you pull her medical license records? Any complaints filed, any disciplinary actions?"
"I'm on it. What are you going to do?"
"Pay Dr. Mendez a visit. See if she's willing to discuss her patient list and research protocols."
"Kari, if she's involved, showing up unannounced could spook her. We need to be strategic about this."
"I'm not going to accuse her of anything. Just ask questions." Kari pulled out of the parking lot, heading toward the address she'd noted from Mendez's website. "If she's innocent, she'll cooperate. If she's not, maybe she'll make a mistake."
"Or she'll lawyer up."
"Then we'll know she's got something to hide."
Maria sighed. "All right. But keep your phone on. If things go sideways, I want to know immediately."
Dr. Mendez's practice was located in an upscale medical complex in North Phoenix. The waiting room had leather furniture and the receptionist looked like she'd stepped out of a luxury car commercial. Kari approached the desk and showed her badge.
"I need to speak with Dr. Mendez. Is she available?"
The receptionist's smile faltered. "Dr. Mendez is with a patient right now. Do you have an appointment?"
"This is regarding an active investigation. I can wait, but I will need to speak with her today."
The receptionist made a call, speaking in low tones Kari couldn't quite catch. A moment later, she hung up and nodded. "Dr. Mendez can see you in fifteen minutes. Please have a seat."
Kari sat, using the time to review her notes.
The pattern was becoming clearer—three elite runners, all preparing for the same race, all connected to a physician whose research involved exactly the kind of extreme conditions that had killed them.
It wasn't proof, but it was the strongest connection she'd found so far.
Kari wasn't sure what she was going to learn by directly confronting Dr. Mendez.
On the one hand, arranging a meeting now risked spooking the doctor, as Maria had pointed out.
On the other hand, it gave Kari the chance to look into a suspect's eyes and judge for herself whether or not this person was hiding something.
Cases were built on evidence. But they were often driven by a detective's instincts, and Kari's instincts had served her well so far.
The door to the back offices opened, and a woman in a white coat emerged.
Dr. Mendez had the lean frame of someone who practiced what she preached, her runner's build evident even beneath the white coat.
She wore her dark hair pulled back in a way that suggested efficiency over style, and when she shook Kari's hand, her grip was firm, her eye contact direct.
"Detective Blackhorse? I'm Dr. Alicia Mendez. Please, come back to my office."