After hands were shaken and introductions made she returned immediately to Gillette. She twined a mass of hair around her fingers and, not caring who heard, said bluntly, "I saw the way you looked at me when you heard I worked for Horizon."

Like all big commercial Internet service providers – AOL, CompuServe, Prodigy and the others – Horizon On-Line was held in contempt by true hackers. Computer wizards used telnet programs to jump directly from their computers to others' and they roamed the Blue Nowhere with customized Web browsers built for interstellar travel. They wouldn't think of using simple-minded, low-horsepower Internet providers like Horizon, which was geared for family entertainment.

Subscribers to Horizon On-Line were known as HOLamers or HOLosers. Or, echoing Gillette's current address, just plain HOs.

Nolan continued, speaking to Gillette. "Just so we get everything on the table, I went to MIT undergrad and Princeton for my masters and doctorate – both in computer science."

"AI?" Gillette asked. "In New Jersey?"

Princeton 's artificial intelligence lab was one of the top in the country. Nolan nodded. "That's right. And I've done my share of hacking too."

Gillette was amused that she was justifying herself to him, the one felon in the crowd, and not to the police. He could hear an edgy tone in her voice and the delivery sounded rehearsed. He supposed this was because she was a woman; the Equal Employment Opportunity Commission doesn't have jurisdiction to stop the relentless prejudice against women trying to make their way in the Blue Nowhere. Not only are they hounded out of chat rooms and off bulletin boards but they're often blatantly insulted and even threatened. Teenage girls who want to hack need to be smarter and ten times tougher than their male counterparts.

"What were you saying about Univac?" Tony Mott asked.

Nolan filled in, "March 31, 1951. The first Univac was delivered to the Census Bureau for regular operations."

"What was it?" Bob Shelton asked.

"It stands for Universal Automatic Computer."

Gillette said, "Acronyms're real popular in the Machine World."

Nolan said, "Univac is one of the first modern mainframe computers, as we know them. It took up a room as big as this one. Of course nowadays you can buy laptops that're faster and do a hundred times more."

Anderson mused, "The date? Think it's a coincidence?"

Nolan shrugged. "I don't know."

"Maybe our perp's got a theme of some kind," Mott suggested. "I mean, a milestone computer date and a motiveless killing right in the heart of Silicon Valley."

"Let's follow up on it," Anderson said. "Find out if there're any recent unsolved killings in other high-tech areas that fit this M.O. Try Seattle, Portland – they have the Silicon Forest there. Chicago 's got the Silicon Prairie. Route 128 outside of Boston."

" Austin, Texas," Miller suggested.

"Good. And the Dulles Toll Road corridor outside of D.C. Start there and let's see what we can find. Send the request to VICAP."

Tony Mott keyed in some information and a few minutes later he got a response. He read from the screen and said, "Got something in Portland. February fifteenth and seventeenth of this year. Two unsolved killings, same M.O. in both of them, and it was similar to here – both victims stabbed to death, died of chest wounds. Perp was believed to be a white male, late twenties. Didn't seem to know the victims and robbery and rape weren't motives. The vics were a wealthy corporate executive – male – and a professional woman athlete."

"February fifteenth?" Gillette asked.

Patricia Nolan glanced at him. "ENIAC?"

"Right," the hacker said then explained: "ENIAC was similar to Univac but earlier. It came online in the forties. The dedication date was February fifteenth."

"What's that acronym?"

Gillette said, "The Electronic Numerical Integrator and Calculator." Like all hackers he was an aficionado of computer history.

"Shit," Shelton muttered, "we've got a pattern doer. Great."

Another message arrived from VICAR Gillette glanced at the screen and learned that these letters stood for the Department of Justice's Violent Criminal Apprehension Program.

It seemed that cops used acronyms as much as hackers.

"Man, here's one more," Mott said, reading the screen.

"More?" Stephen Miller asked, dismayed. He absently organized some of the disks and papers that covered his desk six inches deep.

"About eighteen months ago a diplomat and a colonel at the Pentagon – both of them with bodyguards – were killed in Herndon, Virginia. That's the Dulles Toll Road high-tech corridor… I'm ordering the complete files."

"What were the dates of the Virginia killings?" Anderson asked.

"August twelfth and thirteenth."

He wrote this on the white-board and looked at Gillette with a raised eyebrow. "Any clue?"

"IBM's first PC," the hacker replied. "The release date was August twelfth." Nolan nodded.

"So he's got a theme," Shelton said.

Frank Bishop added, "And that means he's going to keep going."

The computer terminal where Mott sat gave a soft beep. The young cop leaned forward, his large automatic pistol clanking loudly against his chair. He frowned. "We've got a problem here."

On the screen were the words:

Unable to Download Files

A longer message was beneath it.

Anderson read the text, shook his head. "The case files at VICAP on the Portland and Virginia killings're missing. The note from the sysadmin says they were damaged in a data-storage mishap."

"Mishap," Nolan muttered, sharing a look with Gillette.

Linda Sanchez, eyes wide, said, "You don't think… I mean, he couldn't've cracked VICAP. Nobody's ever done that."

Anderson said to the younger cop, "Try the state databases: Oregon and Virginia state police case archives."

In a moment Mott looked up. "No record of any files on those cases. They vanished."

Mott and Miller eyed each other uncertainly. "This's getting scary," Mott said.

Anderson mused, "But what's his motive?"

"He's a goddamn hacker," Shelton muttered. "That's his motive."

"He's not a hacker," Gillette said.

"Then what is he?"

Gillette didn't feel like educating the difficult cop. He glanced at Anderson, who explained, "The word 'hacker' is a compliment. It means an innovative programmer. As in 'hacking together' software. A real hacker breaks into somebody's machine only to see if he can do it and to find out what's inside – it's a curiosity thing. The hacker ethic is it's okay to look but don't touch. People who break into systems as vandals or thieves are called 'crackers.' As in safecrackers."

"I wouldn't even call him that," Gillette said. "Crackers maybe steal and vandalize but they don't hurt people. I'd call him a 'kracker' with a k. For killer."

"Cracker with a c, kracker with a k" Shelton muttered. "What the hell difference does it make?"

"A big difference," Gillette said. "Spell 'phreak' with a ph and you're talking about somebody who steals phone services. 'Phishing' – with a ph – is searching the Net for someone's identity. Misspell 'wares' with a z on the end, not an s, and you're not talking about housewares but about stolen software. When it comes to hacking it's all in the spelling."

Shelton shrugged and remained unimpressed by the distinction.

The identification techs from the California State Police Forensics Division returned to the main part of the CCU office, wheeling battered suitcases behind them. One consulted a sheet of paper. "We lifted eighteen partial latents, twelve partial visibles." He nodded at a laptop computer case slung over his shoulder. "We scanned them and it looks like they're all the victim's or her boyfriend's. And there was no evidence of glove smears on the keys."