BANGKOK (Reuters) - The evidence seized by police investigating Thailand's deadliest bombing includes an apparently damning trove of explosives, fertiliser, and piles of fake passports, but the shabby-looking foreigner they arrested on Saturday remains a mystery.
There has been no word of his nationality, affiliation or whether the evidence seized in a shabby Bangkok apartment block amounts to a smoking gun for the attack on a crowded downtown shrine that killed 20 people two weeks ago.
Reuters interviews with neighbours, investigators and the community in the city suburb of Nong Chok paint a picture of a reclusive and secretive Muslim who seldom ventured beyond the four rooms he occupied in the grimy orange and cream-coloured building.
Police have been tight-lipped - at times cryptic - about the man they indicate is the chief suspect caught on camera leaving a bag at the site of a bombing that shook Bangkok's bustling commercial heart.
They are checking DNA samples and calls made from his phone, but have not indicated the man has said anything since his arrest.
According to a couple who rent a room on the same floor, the suspect was not alone and shared the accommodation with a man of similar ethnicity, who was last seen on Friday.
"There's another; he's much taller," said the man, who requested anonymity because he feared for his safety.
The couple said they instantly recognised the images on newscasts that went viral on social media of the thin, bearded man with a pale complexion and tightly cropped hair.
They had seen him sometimes kneeling and praying in the corridor. On the rare occasions he was spotted outside, he appeared focussed and walked with purpose.
"They're very quiet neighbours," said the man. "The taller man buys food for them."
A person matching the second man's description had spoken only a few words of English while at a nearby food stall, according to vendors who last saw him on Thursday.
Many Thai Muslims and foreigners live in Nong Chok, an area of cheap rents and short leases, where there are colleges, factories, rice paddies, mosques and streets dotted with halal restaurants.
Residents said the suspect was inconspicuous in a transient community of foreigners and university students in the sprawl of one of Asia's most cosmopolitan capitals.
"The building often has foreigners renting rooms," said Khantree Srisombat, 42, who lives in the same block.
"It's normal here."
The building owner who gave only his first name, Anant, said the lease contracts were signed using Turkish identification, but not by the arrested man.
When security forces burst into the building to make the arrest, the man declined to speak, even through a Turkish translator, according to a plain-clothes special branch officer who joined the raid.
The officer spoke to Reuters on condition his name be withheld and said two rooms were strewn with bomb-making materials, including urea fertiliser, TNT, C4, sodium carbonate, large plastic and steel containers, a fuse line, flashlights, screwdrivers and tape.
"The suspect never said a word," the officer added.
Among the passports seized, some had images of the same man, bearing the name Adem Karadag, purportedly Turkish, with birth dates of 1987 and 1985.
Official comments about the man have been opaque, and assessments given often without explanation.
Thai police chief Somyot Pumpanmuang on Saturday insisted the bombing was not terrorism and declared the man's motive was "taking personal revenge for his comrades".
On Sunday security forces searched a low-budget building used by many Muslim residents in nearby Min Buri district. Deputy district police chief Susak Parakkamakul declined to say whether any evidence was found.
Across the road, worshippers at the Al Madanee Mosque, the largest in the area, said they had never seen the suspect.
"I pray here five times a day, every day, and I've never seen him," Qasim Ghulam Mohammad said after prayers on Sunday.
"It's a very bad crime. If he is the bomber, he has to go to jail."
(Writing by Martin Petty; Editing by Will Waterman)