Amporn Jaikorn, 56, a key suspect in major explosions in Nonthaburi and Bangkok, has been detained for fresh questioning after she was released two years ago.
Her detention has sparked rumours that it might have something to do with the arson and bomb attacks in seven provinces, though her lawyer, Benjarat Methian has denied this.
She was a key suspect in a major apartment explosion in Nonthaburi in 2010 and later in another explosion in Min Buri district, Bangkok, in 2014.
After Ms Amporn was detained on the same arrest warrant -- issued on Oct 15, 2014, on charges of possessing, assembling and importing explosive devices. She was taken from her home in Chiang Mai's Hang Dong district to Bangkok by plane late on Wednesday night.
The Min Buri provincial court on Thursday rejected a request to have her released on bail owing to the seriousness of the case.
According to a police investigation report, the 2010 Saman Metta Mansion explosion and the explosion involving a motorcycle on Soi Rat Uthit 25 in Min Buri on March 29, 2014, were connected.
According to the police report, it was the same people who were responsible for both incidents, with Ms Amporn saying she knew Samai Wongsuwan, a suspected bomber and resident of Hang Dong district who died in the blast at Saman Metta Mansion.
Ms Amporn, however, denied any wrongdoing.
Ms Benjarat said she was wondering why her client had been detained again after she had been released, and why police did not find any evidence to implicate her in the Min Buri explosion.
Ms Amporn had been arrested on April 27, 2014, on suspicion of being involved in the March 29, 2014, explosion in Min Buri, said the lawyer, adding that Ms Amporn was later handed over to the Department of Special Investigation before being eventually released.
Ms Benjarat said Ms Amporn had not before been aware of any new warrant used in the arrest. She said her client had no intention of escaping and has lived at her home in Chiang Mai ever since being released amid the previous investigation.
The court is scheduled to hear witnesses in the Saman Metta Mansion explosion on Sept 13-16, said Ms Benjarat.
The Saman Metta Mansion explosion killed four people and injured nine others.
On March 29, 2014 two men were killed when a home-made bomb hidden in a motorcycle they were riding exploded in a car park.