Moon tugged a beard hair. "You weren't aware, foolish of me to assume. Then I suppose you're inquiring again about that tutor he worked for."

"Elise Freeman, Professor. Trey told you about that?"

"A few days ago, he seemed a bit distracted in the lab and I asked him why. He told me he'd just had a strange experience: interrogation by the police."

"We call it interviewing."

Moon smiled. "Be that as it may, Trey felt interrogated. As if you suspected him of something simply because he'd known the woman."

"Contacting a victim's acquaintances is pretty much routine."

"That would make sense," said Moon. "Nonetheless I'm sure most people don't enjoy the experience."

"How long has Trey been missing?"

"He's been absent from the lab for two days and we haven't been able to reach him. One of Trey's virtues is reliability. We're preparing an important paper so his participation is especially important."

"Perhaps," I said, "the pressure got to him."

"What pressure?"

"The paper added to his usual responsibilities."

"Hmm," said Moon. "No, I don't think so. Trey has never been the anxious type."

"Cool under fire. But the interview bothered him."

"He seemed more disappointed than anxious. That someone would think him capable of such violence."

"He described the murder as violent?"

Moon wet his lips with his tongue. "I don't believe we got into details--frankly that kind of thing doesn't interest me. I suppose he meant homicide, in general. Isn't the malicious dispatch of another human being always violent at the core?"

"When you and Trey traveled to Stanford were you together most of the time?"

"That sounds as if you're confirming an alibi."

I smiled.

Moon said, "Contrary to what you might think of academics, we do work hard. That was a work trip, our days were pretty much nine-to-five."

Milo said, "So Trey had evenings to himself."

"I'm his advisor, not his babysitter, I have no idea what he did at night. You might try Juliet Harshberger. She and Trey appear to be a bit of an item."

"You haven't contacted her?"

"I avoid meddling in my students' personal lives but I was contemplating doing just that."

"Where can we find Ms. Harshberger?"

"Most likely here, Lieutenant."

"In this department?"

"Here on campus. She's a grad student in biology."

"Thank you, Professor. Is there anything else you'd like us to know about Trey?"

Moon said, "Obviously I've enjoyed having him in my lab. He's smart and an excellent long-range thinker. In my field, problems often take years, even decades, to solve. Some of the brightest students fade when gratification slows."

"Trey on the other hand..."

"Is able to keep his eye on the core of the problem as well as the eventual goal." Moon stroked his beard. "You don't really think he was involved in murder?"

"Routine questions," said Milo. "Also, we like talking to smart people."

When we were out of earshot, I said, "Nothing like a careful planner."