Authorities and family blame the absence of an "ill" eyewitness for the acquittal of a defendant accused of the murder of a young man whose father afterwards plunged to his death from the 8th floor of the Criminal Court building in Bangkok on Monday.
The murder victim's mother also claimed witnesses in the case had been "influenced".
Pol Col Krisana Patanacharoen, deputy spokesman of the Royal Thai Police, said on Tuesday the police case report on the murder was flawless when it was sent to public prosecutors. The prosecutors' decision to indict the suspect was proof of the quality of the case report.
However, an eyewitness who had been questioned by police interrogators had been unable to testify in court because the witness was in hospital awaiting treatment for mental problems.
The other witnesses and evidence were not strong enough proof on their own, so the court acquitted the defendant, Pol Col Krisana said.
Kosolwat Inthujanyong, deputy spokesman of the Office of the Attorney-General (OAG), insisted on Tuesday that prosecutors had also done their best, but the absence of the witness proved crucial.
He also said police were unable to obtain surveillance camera footage that prosecutors had requested.
Pithak Obsuwan, executive director of criminal litigation, said prosecutors would soon take the case to the Appeal Court, but he was uncertain if the absent eyewitness could be there.
Rewadee Talhasuntorn received the body of her husband at the Police General Hospital in Bangkok on Tuesday. She said she had not suspected he would committed suicide. He had been happy before the court's ruling, expecting the punishment of the defendant.
At the moment, she briefly wanted to follow her husband and die, but someone pulled her back. She would not rule out the possibility if the family does not receive justice later.
Mrs Rewadee said witnesses had been reluctant to testify because influence had been brought to bear on them. She hoped the witnesses would have more empathy for her family at the Appeal Court.
She also said that police interrogators told her family to gather evidence themselves. That forced her husband to quit his permanent job, so that he had time to do it.
Supachai Talhasuntorn, 52, plunged from the 8th floor of the Criminal Court building on Ratchadaphisek Road on Monday after the acquittal ruling.
Two men attacked and stabbed his son Thanit, 23, to death on Soi Prachasongkroh 1 in Din Daeng district, Bangkok, on the night of April 15, 2016, which was during the Songkran festival.
One of the attackers was identified as Nathapong Ngoenkhiri, 19, who was charged and subsequently acquitted. The other was a boy aged 16, who is on trial in the juvenile court.