The suicide bomber in last week's deadly attack on Israeli tourists in Bulgaria entered from neighbouring Romania, spoke decent Russian and had a female companion, local media reported on Monday.
Citing investigators probing last Wednesday's bombing of a bus at Burgas airport that killed five Israeli tourists and the driver, television channel bTV said that the attacker was in the city of Varna for at least a day before the bombing.
While in Varna, which is further up the Black Sea coast from Burgas, he left behind "biological evidence" at a hotel, BTV said.
Newspaper Troud meanwhile reported that police were looking for a woman believed to have been staying in the Varna hotel with the bomber, naming it as the three-star Hotel Perfekt.
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This woman is also believed to be linked to a possible second man whom police think may have been the bomber's accomplice, the newspaper said, also citing unnamed investigators.
The daily also cited a taxi driver who said he drove the suicide bomber from Ravda and Pomorie, two small towns north of Burgas, the day before the attack, and that he spoke "decent Russian."
Bulgarian authorities have declined to comment on the investigation, saying only that they believe the bomber was aged around 36, had a fake US driving licence, was not Bulgarian and had been in the country "not less than four days."
They have also released CCTV footage from the airport of the man they believe was the suicide bomber. He is shown wearing typical tourist clothes and has long hair, possibly a wig, and appears to be white.
Israel has blamed the deadliest attack on its citizens abroad since 2004 on Iran and its "terrorist proxy" Hezbollah, the Lebanese militia. Tehran has denied any involvement.