Bangkok (dpa) - Thai police Wednesday offered a reward of 1 million baht (28,000 dollars) for information helping them capture the suspect behind the blasts in Bangkok this week, and said he was helped by a local network.
The police released a sketch to the public showing a spectacled man with mid-length curly hair.
"I believe there is more than one person behind this. There is a network," Police Chief Somyot Pumpanmuang said.
"A foreigner couldn't commit this act alone. There has to be Thai people helping this guy commit the act."
Prime Minister Prayut Chan-o-cha warned the suspect on Wednesday to "quickly turn yourself in otherwise you might be killed by security forces."
"People who know him, relay this message."
Police revealed late Tuesday that they had narrowed their search to a suspect seen on closed-circuit footage before the blast.
The man carried a black backpack to the site, and was seen leaving without it shortly before the blast.
(1) 18.37.51 captured by Hyatt's camera, the suspect (in yellow T-shirt) got off tricycle taxi, reached for backpack
(2) 18.37 tricycle left, suspect walked towards Erawan Shrine
(3)18.51 suspect seen at Erawan Shrine
(4) 18.51 captured by shrine's camera, suspect sat down on bench near Phloenchit Road
(5) 18.52 suspect placed backpack on the bench and left
(6) 18.53 captured by Hyatt's camera, suspect walked towards Soi Mahadlekluang, BTS Rajdamri Station
(7) 18.54.43 suspect on the way to BTS station
(8) 18.55.18 the bomb exploded