Police said on Tuesday they had discovered new information timelines lending credence to the theory that 28-year-old motor show model Prawrawee "Yoko" Sahatthatphong did indeed take her own life on Nov 1.
The new information shows the model, who was found dead in her Ekkamai condominium, purchased a bottle of cyanide online in September for 33,000 baht, they said.
Pol Maj Gen Wittawat Chinkham, commander of the Metropolitan Police Division 5, said more time is needed to fill in all the blanks, but the police now have clear evidence, including her order list history, transaction data and receipt of a parcel.
He said a suicide note was also found addressed to her boyfriend, along with antidepressant medication, and the word "cyanide" was in her phone's search history.
CCTV footage also showed that Prawrawee did not leave her condo prior to her death, and no one else entered it, Pol Maj Gen Wittawat said.
The autopsy showed she died from cyanide poisoning, with at least 1.26 microgrammes per millilitre found in her bloodstream.
"This case is not complicated. We are waiting for all of the evidence, including Prawrawee's movements during the night of Oct 30 and some forensic evidence," he said.
Police also summoned Prawrawee's boyfriend about a "secret" video clip mentioned by Prawrawee's mother, he added. The mother believed the clip contained a set of rules meted out by the boyfriend if Prawrawee wanted to stay in the relationship.
The boyfriend admitted to sending the clip on Oct 31, but further details cannot be disclosed, Pol Maj Gen Wittawat said.