Chiron Corp. was bombed last week in what may have been the latest and most violent offense in a string of harassment incidents brought by animal rights protesters.

The company said that between 3 a.m. and 4 a.m. local time on Thursday, two homemade bombs exploded at its headquarters in Emeryville, Calif., though neither resulted in injuries or major property damage aside from broken windows.

The next day, a group called the Revolutionary Cells claimed responsibility for the act, though the claim was not validated. The group signed a news release rife with threatening rhetoric as the "animal liberation brigade."

"There will be no quarter given, no more half measures taken," a portion of the release read. "You might be able to protect your buildings, but can you protect the homes of every employee?"

The bombs, which the group described as "a small surprise of two pipe bombs," blew up about an hour apart. Police later located a third bomb on the grounds and safely detonated it. The incident caused the company to shut down operations for half the day, though its employees returned for a regular workday on Friday. Of Chiron's worldwide staff of nearly 4,000, about half work at the campus located between Oakland and Berkeley.

"I'm a former prosecutor, and this appears to be a serious crime and intent to do not only property damage but great bodily harm," Carl Feldbaum, the president of the Biotechnology Industry Organization in Washington, told BioWorld Today. "Frankly, I don't give a damn about the motive. It just deserves to be thoroughly investigated and forcefully prosecuted."

Local and federal law enforcement authorities, including the FBI and ATF, are pursuing the case.

"We certainly have taken appropriate security measures to protect our employees and facilities, following the advice given to us by law enforcement authorities," John Gallagher, Chiron's manager of media relations, told BioWorld Today. "But we don't know who is responsible or what the motives were for the explosions. Any speculation that it was animal rights activists would be speculation. I don't think law enforcement officials have determined what the motives were or who was responsible. That would be up to them."

But he acknowledged that Chiron's executives recently have found themselves subject to harassment by animal rights protesters, who have become increasingly radical in their tactics to draw attention to their cause. At the heart of the issue is Chiron's relationship with Huntingdon Life Sciences plc, an animal-testing firm that two years ago essentially disbanded its UK headquarters and moved to the U.S. in the wake of animal rights activists who sometimes turned violent. Protestors assaulted its CEO in February 2001.

Chiron, which has used Huntingdon's services in the past, has no studies under its stewardship at the moment. Gallagher declined to detail the potential of Chiron's future relationship with Huntingdon.

"We follow stringent guidelines in ensuring that the animals that are necessary for research and testing are treated in the most ethical manner possible," he said.

Huntingdon, whose executives and investors were harassed at the urging of a group called Stop Huntingdon Animal Cruelty (SHAC), delisted its shares from the London Stock Exchange and shifted trading and facilities to the U.S. early last year. The American arm of the animal rights group, SHAC USA, has publicized Chiron's link to the contract research business.

The Princeton, N.J.-based organization disseminates bimonthly newsletters and e-mail alerts to about 3,000 subscribers.

"SHAC USA is a mouthpiece organization," Kevin Jonas, its spokesman, told BioWorld Today. "We publish all news and information related to Huntingdon Life Sciences, and the international campaign to close it down. To that extent, we don't censor or judge any actions, and any actions posted on our website may or may not represent the views of its host or contributors."

He said that on five separate occasions, Huntingdon has been infiltrated with hidden cameras that allegedly recorded acts of animal cruelty and scientific fraud. Jonas also said SHAC has sought to present such findings, as well as more than 600 violations of good laboratory practices, to executives at Chiron and other Huntingdon customers. But, he said, SHAC has been rebuffed.

"So our message to these companies is that it's time for protest activity," Jonas said. "All across America and across the world, this is what's happening. People are staging protests, writing letters, doing publicity stunts, and now as we've seen, some groups are resorting to more drastic political direct action."

Prior to the bombings, Chiron executives had been subject to home residence demonstrations such as the placement of false tombstones in their yards, early morning wakeups and harassing phone calls. But he said SHAC does not and would not support violence as part of the cause. Its website lists locations for 44 U.S. companies, most of them pharmaceutical and biotech firms, that it said contract with Huntingdon. Some of them and their employees also have been the target of acts of vandalism.

Jonas added that although SHAC may share the same ideological goals relative to animal testing, the organization would neither subscribe to violence nor recommend such actions to its supporters. The statement from the Revolutionary Cells was much more menacing.

"If you choose to continue your relations with [Huntingdon], you will no longer be subject only to the actions of the above-ground animal rights movement, you will face us," the release read. "This is the endgame for the animal killers and if you choose to stand with them you will be dealt with accordingly."

Though BIO has enacted safeguards related to protests at its gatherings and other events, Feldbaum said no industry-wide guide exists for dealing with specific acts of violence at particular companies. But he said criminal prosecution would be an appropriate action.

"This is an unprecedented and miserable event," Feldbaum said. "I think prison time in cases like this tends to be a real deterrent. I don't know what the state prison is that serves Emeryville, but I'm pretty sure it's not a nice place."

He said BIO has not kept statistics on crimes against biotech companies. But the organization has an internal security committee and a group of safety-savvy companies that together serve as a forum to share safeguard tips with others in the industry.

And chances are, many in the industry will be paying mind.