Bulgaria has sent DNA samples from the Burgas suicide bomber's body to U.S. intelligence agencies, but the Americans have not yet found a match with any former detainee at Guantanamo Bay.
The Bulgarians have also sent information to Interpol and police forces around the world in an attempt to identify the terrorist. Bulgarian and Israeli investigators collected evidence from the Burgas airport, where five Israelis and the Bulgarian bus driver were killed.
Bulgarian Interior Minister Tsvetan Tsvetanov, who is in charge of the investigation, denied rumors in the international media about the bomber's identity and said there was no proof that Hezbollah was behind the attack.
"In the last 48 hours we have gathered a lot of information that could achieve progress in the investigation," Tsvetanov told reporters Friday. "Experts are gathering information and we are sharing it with all relevant parties," he said, noting the close cooperation between Bulgaria and Israel.
"[The bomber] was not in Guantanamo and there is no proof that he was sent by Hezbollah," Tsvetanov said, adding that information not approved by Bulgaria's Interior Ministry should be treated with caution.
"It's important for us to understand when he entered Bulgaria, and how long he was in the country before the attack," Tsvetanov said. "We know he was in Bulgaria for at least four days. But we don't know yet whether he had accomplices or whether he acted alone."
In addition to DNA samples, samples of the explosives were taken in an attempt to link it with previous attacks. The bomber was carrying about three kilograms of explosive.
Investigators assume that such an attack could not be carried out by one person, since the planning, surveillance of buses and assembly of the explosives would usually involve more than one terrorist.
On Friday, Bulgarian television showed images of an alleged U.S. citizen suspected of aiding the bomber. Local media reported that this information had been provided by a man who said he recognized the terrorist from photos published immediately after the attack. Tsvetanov has yet to confirm whether this information is reliable.
According to Rabbi Haim Tavardovitch of the local Chabad House, "We have received no information regarding this matter. If there really is a terrorist wandering around here, we have to know."
On Friday, some 200 Israelis arrived at the house, where Shabbat dinner is offered free. The place was guarded by local policemen.
Chabad officials said that since their facilities are perceived as possible attack targets, they usually receive information about any threats. But they have not yet been contacted by local security officials. Israeli officials are trying to persuade the Bulgarians to increase security at sites favored by Israeli tourists.
On Saturday, life in Burgas seemed back to normal, with tourists roaming around town. The airport functioned as usual and security measures appear to have been eased.
Prime Minister Benjamin Netanyahu has accused first Iran and then Hezbollah of carrying out the bombing. On Friday, George Little, the Pentagon press secretary, told reporters that the attack "does bear the hallmarks of Hezbollah."
Little turned aside a request to characterize the signs of an Hezbollah attack or how it could be distinguished from one by, for instance, Al-Qaida, which is not linked to Iran.
With reporting by Reuters.
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