Authorities have also been monitoring arrivals and departures of the suspects’ associates, their activities, and their financial transactions here by scrutinising documents, security camera footage and other sources of information.
A source identified the fifth suspect as Nikkhafard Javad, 52. On the morning of February 14, the Iranian was seen leaving the rented house on Soi Pridi Banomyong where the other suspects had lived, carrying a bag. Hours later, an explosion erupted at the house and more blasts followed nearby.
Police believe Javad might have made bombs or taught bombmaking techniques to three other suspects now in detention.
Saeid Moradi, 28, was arrested on Tuesday at the scene of an explosion near the house. Mohammad Hazaei, 42, was nabbed at Suvarnabhumi Airport on the same day. Another suspect, Masoud Sedaghatzadeh, 31, was arrested in Malaysia.
The only female suspect, 32yearold Laila Rohani, is believed to have fled Thailand.
Deputy Metropolitan Police commissioner MajGeneral Anuchai Lekbamrung expected the court to issue an arrest warrant for the fifth suspect in a day or two.
“This fifth suspect will be facing charges of making explosives, unauthorised possession of explosives and causing explosions endangering others,” he said.
An informed source said Javad was seen in the Thong Lor and Klong Tan areas when the explosions took place in Bangkok on Tuesday.
Metropolitan Police Commissioner LtGeneral Winai Sodsong yesterday said investigators had already questioned 16 witnesses and collected additional evidence from another residence rented by Rohani.
“We have found some stickers and cement blocks. Officials are examining the items,” he said. He added that the stickers contained symbols that looked like Arabic characters.
Winai said the whereabouts of a sixth suspect, a man who accompanied Rohani when she rented the house on Soi Pridi Banomyong, were not known.
National Security Council secretarygeneral Wichean Potephosri, meanwhile, said authorities would be seeking the extradition of Sedaghatzadeh.
Deputy Prime Minister General Yuthasak Sasiprapha said it remained unclear whether the bomb blasts in Thailand were related to similar incidents in Israel and Georgia.
“Thai police are investigating the blasts here,” he said.
On Israel’s suggestion that Iran was behind the blasts in Bangkok, Yuthasak said relevant authorities were working to find out what really happened.
“We are friends to both Iran and Israel,” the deputy prime minister said.
Winai said security officials would keep a closer eye on tourist spots such as the Nana and Klong Tan areas, and Khao San Road.
According to police, three of the Iranian suspects went to Pattaya earlier this month. An escort girl who had accompanied them said the men seemed interested in terrorismrelated news but did not carry or buy any weapons.