"Is that so very difficult?" asked Sigrid.

"Difficult!" the girl hooted. "Boy, it's plain you never took Oscar Nauman's color class! What time is it? Five? God! No wonder I'm feeling so empty-I've been down here working on this thing since eleven this morning. It's really a hairy problem," she explained. "See, the assignment was to go from dark to light, any color, in nine equal steps."

Sigrid looked puzzled, so the girl tried again. "Look, I started with this dark red square, right? So dark it's almost black. Then I put down another square that's a little more of a clear red, right?"

Sigrid nodded.

"Now let's say I next tried one of these that's even lighter from further down at the pink end. I'm still going from dark to light, but the differences between this second and third shade is greater than that between the first and second. See? It's got to step down exactly equal."

Again Sigrid nodded. "But it still doesn't sound very difficult."

"Want to try? Be my guest," said the girl, pushing all the extra little squares toward Sigrid. "I must have mixed a hundred and fifty different shades."

Intrigued, Sigrid began lining them up as the girl pasted her own final combination of the white paper.

"There," she said after a few moments.

The girl examined Sigrid's maiden effort and shook her head kindly, "Not bad for a first time, but the change is too great between your third and fourth, and you've only used seven shades. Nine's the magic number, no more, no less. Seven's easy and twelve's a snap. Nine's the bastard."

While the girl cleaned her brushes and put away her tools, Sigrid idly shifted the squares. "I had no idea you could spend a whole semester on just color," she mused.

"A semester? You could study it for years," the girl assured her, "and still not learn half the stuff Professor Nauman knows about it. Which is weird if you think about it. I mean, look in the school catalog.

Everybody else has a string of letters after their names-M.F.A.'s Ph.D.'s Nauman has nothing. I heard he didn't even finish high school."

"But he's a good teacher?"

"The best if you're serious about learning rock-bottom, basic fundamentals. Some of the staff, their stuff's based on sneaky little tricks of technique, see? So they're stingy about what they'll share when they're teaching. Afraid you'll steal it. But Nauman's generous. He'll give you everything he has because his work's built on solid truth. If you could imitate it, you wouldn't want to because you'd know enough to have your own perception of truth, see?"

"Professor Nauman must be very popular," Sigrid said, recognizing an enthusiast.

"Nope! No way. Lots of people hate his guts," said the girl cheerfully. "Students and staff. He gets impatient with stupidity and laziness, and there's lots of both floating around. They're afraid of him. The man's brilliant, see? And sometimes he forgets the rest of us aren't and says what's on his mind without even realizing that he's cutting everybody to splinters. Hey, you through playing with those?" she finished, ready to sweep the superfluous squares of red tones into a wastebasket.

"You're going to throw them away? After all the time you spent making them?"

"Sure! I've got the nine I need. Hey, do you want them? Take them," she said magnanimously. "They'll drive you crazy, but it really is a good exercise for training your color sense."

"Thank you," Sigrid said formally. She collected solitaire games, and this one seemed more engrossing than many.

The girl unearthed a manila envelope, which she filled with the color squares and gave to Sigrid before carefully carrying away her completed project. "I'm going to leave it on Nauman's desk," she said proudly. "He didn't think any of us could do it in less than three days. See you!"

With a friendly wave of her hand the girl was gone, still unaware that murder had occurred overhead while she wrestled with color.

Sigrid followed more slowly. If a student's casual assessment meant anything, it would be a mistake to ignore the possibility that the poisoned coffee might have been meant for Nauman instead of Riley Quinn.

Jealousy and resentment could be potent corrosives.

"Oh, there you are. Lieutenant," said Detective Tildon from the doorway of the print workshop. With him was the uniformed officer who'd been sent to collect Mike Szabo. An earnest young rookie, he looked somewhat abashed at having to report failure.

"Sorry, ma'am," he said, "but they told me Szabo took off as soon as he heard about the murder. Not a word to anybody-just up and went, though he was supposed to work till seven tonight. I did get his home address for Detective Tildon."

Tillie touched his clipboard in affirmation that Szabo's address was officially noted.

Sigrid inclined her head. "Very good, Officer. Thank you."

"You still want someone posted upstairs?" he asked.

"No, it's no longer necessary," Sigrid replied. The rookie nodded and left.

"Is this going to take very long?" Lemuel Vance complained as Sigrid and Tillie joined him inside the studio. "I've got a class meeting here at six, and I haven't day."

"Only for the day people in the department," he said bitterly. "Administration's decreed that since the Continuing Ed. students had no contact with Quinn, canceling classes out of respect for his memory would be, quote, meaningless, unquote. They're ignoring the fact that everyone who teaches at night was Quinn's colleague."

In light of his earlier calm over Quinn's death Sigrid interpreted his present mood as resentment at not getting a night off, and she directed his attention to the supply closet where the chemicals were housed.

"If the stuff that killed Riley really did come from here, maybe we'd better cancel my etching class anyhow. Admin, couldn't object if you told them you don't want things disturbed," Vance said hopefully, looking around the small room.

"That won't be necessary," Sigrid said coldly, crushing his plans for an early getaway. "Everything's been photographed and examined for fingerprints. Tell me,

Lemuel Vance's eyes followed hers to the red-mustachioed jar. "It's for etching aluminum plates. Mostly we use copper or zinc, but I like the kids to know how to do it all. Or at least be familiar with the techniques. Funny," he said slowly, "I just ordered a fresh batch last month. The first in-hell, must be nearly five years."

"Oh?"

"Yeah. Like I said, we don't use much aluminum. As you can tell, that jar's an old one. I just dumped the new stuff in on top. But it was delivered to the office upstairs. I remember Sandy reading off all the warnings out loud. Jesus! Now I remember Riley saying it sounded like something the cafeteria could use to jazz up the soup!"

"Who else was there?" Sigrid asked sharply.

Vance shrugged. "I don't know. The usual crowd, I suppose."

"Ross, Saxer, Leyden?"

Vance nodded.

"Harris, Simpson… or Szabo?"

"No. Szabo comes up to talk to Leyden once in a while, but that's usually in Leyden's office, not out with the rest of us in Sandy 's office." Vance's brow furrowed in deeper concentration. "I don't remember Bert Simpson. Harris? No-Oscar was right about him not coming up much. Who else? David Wade definitely wasn't because he always sits on the corner of Sandy 's desk, and that's where Jake Saxer was leaning to read off the antidote. Not that you're interested in Wade, I guess, but he's usually up there every break. Young love in bloom, you know.

"Oscar was there, too. He told me to be sure and warn the kids again about how dangerous these chemicals can be. As if I don't read them the riot act every time they touch the knob of this closet door!"

Remembering his facetious remarks earlier about "an eye here, a hand there," Sigrid was bemused by his indignation.