Authorities in Thailand have widened investigation into a series of deaths that have gripped the nation, following the arrest of a woman, suspected of killing 13 people using pills laced with cyanide.
Sararat Rangsiwuthaporn, 36, was charged with premeditated murder of one victim, while the other deaths were still under investigation, police said.
She has denied wrongdoing.
"This case is a premeditated murder," national police chief Damrongsak Kittipraphat said on Thursday, referring to a victim with whom Sararat had been travelling, whose family had raised suspicions with authorities.
Families of other people who had died and had links to Sararat have also since come forward, suggesting those deaths were also suspicious, according to local media. Sararat was taken into custody on Wednesday,
"We have evidence to link her to the (cyanide)," police colonel Anek Thaosuparp said separately, adding that she may have had access to the substance through a store run by her older sister.
Police said those who had died were known to Sararat and her motive may have been financial, according to broadcaster ThaiPBS.
They added one woman had survived Sararat's poisoning attempt and was now being questioned.
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