"It's called Detective. It looks for things that aren't inside a computer." He explained for the benefit of the non-CCU cops. "When your computer runs, the operating system -like Windows – stores parts of the programs it needs all over your hard drive. There're patterns to where and when it stores those files." Indicating the disk, he said, "That showed me that a lot of those bits of programs'd been moved to places on the hard drive that make sense only if somebody was going through her computer from a remote location."

Shelton shook his head in confusion.

But Frank Bishop said, "You mean, it's like you know a burglar was inside your house because he moved furniture and didn't put the pieces back. Even though he was gone when you got home."

Gillette nodded. "Exactly."

Andy Anderson – as much a wizard as Gillette in some areas – hefted the thin disk in his hand. He couldn't help feeling impressed. When he was considering asking Gillette to help them, the cop had looked through some of Gillette's script, which the prosecutor had submitted as evidence in the case against him. After examining the brilliant lines of source code Anderson had two thoughts. The first was that if anyone could figure out how the perp had gotten into Lara Gibson's computer it was Wyatt Gillette.

The second was pure, painful envy of the young man's skills. Throughout the world there were tens of thousands of code crunchers – people who happily churn out tight, efficient software for mundane tasks – and there were just as many script bunnies, the term for kids who write wildly creative but clumsy and largely useless programs just for the fun of it. But only a few programmers have both the vision to conceive of script that's "elegant," the highest form of praise for software, and the skill to write it. Wyatt Gillette was just such a codeslinger.

Once again Anderson noticed Frank Bishop looking around the room absently, his mind elsewhere. He wondered if he should call headquarters and see about getting a new detective on board. Let Bishop go chase his MARINKILL bank robbers – if that's what was so goddamn important to him – and we'll replace him with somebody who at least could pay attention.

The CCU cop said to Gillette, "So the bottom line is he got into her system thanks to some new, unknown program or virus."

"Basically, that's it."

"Could you find out anything else about him?" Mott asked.

"Only what you already know – that he's been trained on Unix."

Unix is a computer operating system, just like MS-DOS or Windows, though it controls larger, more powerful machines than personal computers.

"Wait," Anderson interrupted. "What do you mean, what we already know?"

"That mistake he made."

"What mistake?"

Gillette frowned. "When the killer was inside her system he keyed some commands to get into her files. But they were Unix commands – he must've entered them by mistake before he remembered her machine was running Windows. You must've seen them in there."

Anderson looked questioningly at Stephen Miller, who'd apparently been the one analyzing the victim's computer in the first place. Miller said uneasily, "I noticed a couple lines of Unix, yeah. But I just assumed she'd typed them."

"She's a civilian," Gillette said, using the hacker term for a casual computer user. "I doubt she'd even heard of Unix, let alone known the commands." In Windows and Apple operating systems people control their machines by simply clicking on pictures or typing common English words for commands; Unix requires users to learn hundreds of complicated codes.

"I didn't think, sorry," the bearish cop said defensively. He seemed put out at this criticism over what he must have thought was a small point.

So Stephen Miller had made yet another mistake, Anderson reflected. This had been an ongoing problem ever since Miller had joined CCU recently. In the 1970s Miller had headed a promising company that made computers and developed software. But his products were always one step behind IBM's, Digital Equipment's and Microsoft's and he eventually went bankrupt. Miller complained that he'd often anticipated the NBT (the "Next Big Thing" – the Silicon Valley phrase for an innovation that would revolutionize the industry) but the "big boys" were continually sabotaging him.

After his company went under he'd gotten divorced and left the Machine World for a few years, then surfaced as a freelance programmer. Miller drifted into computer security and finally applied to the state police. He wouldn't've been Anderson's first choice for a computer cop but, then again, CCU had very few qualified applicants to choose from (why earn $60,000 a year working a job where there's a chance you might get shot, when you can make ten times that at one of Silicon Valley's corporate legends?).

Besides, Miller – who'd never remarried and didn't seem to have much of a personal life – put in the longest hours in the department and could be found in the dinosaur pen long after everyone else had left. He also took work "home," that is, to some of the local university computer departments, where friends would let him run CCU projects on state-of-the-art supercomputers for free.

"What's that mean for us?" Shelton asked. "That he knows this Unix stuff."

Anderson said, "It's bad for us. That's what it means. Hackers who use Windows or Apple systems are usually small-time. Serious hackers work in Unix or Digital Equipment's operating system, VMS."

Gillette concurred. He added, "Unix is also the operating system of the Internet. Anybody who's going to crack into the big servers and routers on the Net has to know Unix."

Bishop's phone rang and he took the call. Then he looked around and sat down at a nearby workstation to jot notes. He sat upright; no hacker's slouch here, Anderson observed. When he disconnected the call Bishop said, "Got some leads. One of our troopers heard from some CIs."

It was a moment before Anderson recalled what the letters stood for. Confidential informants. Snitches.

Bishop said in his soft, unemotional voice, "Somebody named Peter Fowler, white male about twenty-five, from Bakersfield 's been seen selling guns in this area. Been hawking Ka-bars too." A nod at the white-board. "Like the murder weapon. He was seen an hour ago near the Stanford campus in Palo Alto. Some park near Page Mill, a quarter mile north of 280."

"Hacker's Knoll, boss," Linda Sanchez said. "In Milliken Park."

Anderson nodded. He knew the place well and wasn't surprised when Gillette said that he did too. It's a deserted grassy area near the campus where computer science majors, hackers and chip-jocks hang out. They trade warez and swap stories, smoke weed.

"I know some people there," Anderson said. "I'll go check it out when we're through here."

Bishop consulted his notes again and said, "The report from the lab shows that the adhesive on the bottle is the type of glue used in theatrical makeup. A couple of our people checked the phone book for stores. There's only one in the immediate area – Ollie's Theatrical Supply on El Camino Real in Mountain View. They sell a lot of the stuff, the clerk said. They don't keep records of the sales but they'll let us know if anybody comes in to buy some.

"Now," Bishop continued, "we might have a lead on the perp's car. A security guard in an office building across the street from Vesta's, the restaurant where he picked up the Gibson woman, noticed a late-model, light-colored sedan parked in the company lot around the time the victim was in the bar. He thought somebody was inside the sedan. If there was, the driver may've gotten a good view of the perp's vehicle. We should canvass all the employees in the company."

Anderson said to Bishop, "You want to check that out while I'm at Hacker's Knoll?"