The bomb attack that killed at least 20 people at Bangkok's Erawan shrine on Monday was carried out by a "network" of people, according to Thailand's chief of police.
"I don't suspect one person, I suspect many people," police head Somyot Pumpanmuang said. "I am confident that there are Thais involved but I am not saying it is just Thais or that there are foreigners."
He also told reporters that authorities had not yet been able to establish the nationality or whereabouts of the main suspect for the bombing, though they are currently keeping watch for him at Thai borders.
Bangkok's Southern Criminal Court later issued an arrest warrant for the unidentified "foreign" man, for charges including conspiracy to commit pre-mediated murder, as well as charges related to the possession of unauthorized explosives and weapons.
The incident was the "worst ever in Thailand," Prime Minister Prayuth Chan-ocha has said, while vowing to hunt down those responsible.
Those killed included several Thai victims, six Chinese, a Malaysian family of four, an Indonesian, a Singaporean woman, and a British teenager.
The latest announcements from the police came after Major General Weerachoon Sukhontapatipak, a spokesman in the military government, told the BBC that authorities are "quite close" to identifying the suspect who appears in widely circulated security camera footage captured shortly before the explosion. The man — wearing a yellow T-shirt — places a backpack on a bench before leaving without it.
Thai police have also released a sketch of the suspect, drawn from the the video. Along with this, a reward of 1 million baht, or more than $28,000, is on offer for anyone who can provide further information on the people behind the bombing.