Revenge eyed as motive in terror tip

Law enforcement officials said yesterday they were investigating whether the tipster who told authorities about four Chinese nationals and two Iraqis plotting an attack on Boston had labeled them terrorists to exact revenge for being cheated in a smuggling or drug operation.

''Could it be a hoax? That's a possibility," said US Attorney Michael J. Sullivan, who accompanied Governor Mitt Romney at a media briefing at the State House yesterday. Both sought to assure the public that the tip remains uncorroborated and that there is no cause for alarm.

''We can't even say for certain that they're in the country," Sullivan said.

On Wednesday, the FBI and Sullivan's office released the names and photos of four Chinese nationals -- Zengrong Lin, Wen Quin Zheng, Xiujin Chen, and Guozhi Lin -- who are being sought for questioning after they were identified by an anonymous caller as terrorists who had plans to obtain nuclear material.

Investigators are also now seeking information on another 10 people mentioned in documents the caller left for authorities, local law enforcement officials confirmed yesterday.

The officials, who spoke on condition of anonymity, provided new details yesterday about what set off the investigation.

The tipster called the California Highway Patrol from Mexico late Monday night and said he had helped smuggle the four Chinese nationals, along with two unidentified Iraqis, into the United States and that they were expected to arrive in Boston, via New York, in four days, the officials said. The caller said that ''nuclear oxide" or ''nuclear fiber" was going to be smuggled to the group through a tunnel system in Mexico into lower California, they said.

The unidentified caller directed police to a package he had tossed over a border fence into California with three visas that had been issued to three of the Chinese nationals by the Mexican embassy in Beijing and a Chinese identity card for the fourth, the officials said.

According to one official, inside the package were airline ticket stubs indicating that the four had flown from Beijing to Mexico City. Some documents in the package, including baggage claim tickets, contained 10 additional names, but it was unclear what their connection was to the six or whether they are aliases for them.

The Associated Press reported last night that nine of the additional names are Chinese: Yu Xian Weng, a woman either 40 or 41; Quinquan or Quiquan Lin, 21; Liqiang Liang, 28; Min Xiu Xie, 27; Xiang or Xing Wei Liu, 22; Mei Xia Dong, 21; Xiuming Chen; Cheng Yin Liu; and Zao Yun Wang. The 10th name is Jose Ernesto Beltran Quinones, of unknown age or national origin, according to the AP. The FBI said that none of the 10 appeared previously on any kind of watch list, the AP reported.

Authorities say it's common for smugglers to seize travel documents from their human cargo and keep them until they are paid for their services.

The threat about nuclear material, along with the tipster saying that the four Chinese are chemists, prompted fear among some law enforcement officials of a so-called dirty bomb: a conventional, or nonnuclear, explosive laced with radioactive components.

Romney, Sullivan, and Mayor Thomas M. Menino all downplayed the threat yesterday, emphasizing that there was nothing to back up the caller's claims. Romney said he canceled his plans to attend President Bush's inauguration to return home Wednesday night and show the public there's no reason to panic.

''I was concerned that things would spin out of people's consciousness and seem to become more serious than they actually are," he said. ''It's our hope that this turns out to be an invalid hoax of some kind, and yet we take these things seriously."

The tipster also gave police the names of a San Diego used car dealer and his girlfriend, contending that they were involved in a smuggling ring and in drug dealing, according to several law enforcement officials. The car dealer has previously been investigated as a possible drug dealer by federal and state officials in California, according to a member of Boston's Anti-Terrorism Advisory Committee.

Some investigators speculated that the tipster may have been seeking revenge against the Chinese nationals after being cheated out of money for ferrying them across the border; others said the mention of the used car dealer suggests a possible link to drug trafficking.

''It is not uncommon to see people who are somehow or another disgruntled to lob that allegation, particularly when it's anonymous," said one local law enforcement official, noting that calling someone a terrorist is guaranteed to bring swift attention.

The official said that even if the investigation ultimately shows that the four Chinese have no terrorist ties, the caller could get revenge against them by having their photos plastered throughout the country and perhaps being deported.

Sullivan said that since alerting the public on Wednesday about the supposed threat and releasing the names and photos of the four Chinese, the FBI's Joint Terrorism Task Force has uncovered information about the backgrounds of the people, but nothing to make them more alarmed.

None of the four Chinese nationals have criminal records, and their names don't appear on any watch lists or databases that federal investigators have searched, Sullivan said.

Nevertheless, Boston and the region remained on high-alert yesterday.

Massport officials are taking the terror threat seriously and have increased security, including patrols, according to Dennis Treece, director of corporate security.

''We're taking it pretty seriously," he said.

MBTA Deputy Chief of Police John Martino said T police have also increased security in response to the threat. He said the T has activated radiation detectors it uses whenever the city is on higher-than-normal security alert.

T personnel were also given pictures of the four Chinese nationals to distribute to stations, which resulted in a couple of dozen tips. None have panned out, Martino said.

''People have believed they have seen one or more of the suspects," he said.

And Bruce Cheney, director of the division of emergency services in New Hampshire, said his office was asked to put the state's radiological response teams on standby.

Authorities in Mexico, meanwhile, gave conflicting information about whether the US government had sought help in the case from their Mexican counterparts.

Government Secretary Santiago Creel, whose office oversees national security, said yesterday that he had no information about the threat and had not been asked for help from the US government.

But Agustin Gutierrez Canet, a spokesman for President Vicente Fox, said Mexico had investigated it, as it does all such reports. There was no evidence, he said, that any Chinese nationals had crossed over into the United States from Mexico.

And US officials in Mexico said an investigation involving agents from both countries had been underway since Wednesday. Diana Page, a spokeswoman at the US embassy in Mexico City, said that ''thanks to the full cooperation of the Mexican government, we are investigating."

She said it was possible that US officials had not directed their request for help through Creel's office, and had instead turned directly to Mexican border officials.

Residents and workers in downtown Boston yesterday were incredulous that the four Chinese nationals would be involved in such a plot, saying they couldn't believe that would-be terrorists would give their photographs and names to a smuggler if they had such violent intentions.

''I can't say this is impossible, but it's unlikely," said Kenny Lu, a native of Taiwan who owns DaDa Hair Studio on Essex Street.

Others said they are following the general advice of their local leaders: Do what you usually do.

''I'm not afraid," said Anne Heffernan, an accountant from Essex. ''I think officials would be far more adamant if this was true."

Donovan Slack and Patricia Wen and of the Globe staff, and correspondents Marion Lloyd, Madison Park, and Janette Neuwahl contributed to this report.