Ms Nuttha, a 37-year-old single mother, arrived at the station at about 8pm, looking on helplessly as police ushered her son out of an interrogation room.
Upon seeing his mother, Tew told her: "Mum, please don't worry. I didn't do it. I know nothing." He was then sent to the Juvenile Observation and Protection Centre in Khon Kaen. along with his cousin No, 17. Another cousin Petch, 20, was sent to Kalasin Prison.
Police alleged the three shot six students from Huai Phueng Vocational College, killing three and wounding three, on the morning of July 10. One of the students who was injured in the attack told police that he and five others went to a night entertainment venue, leaving at about 3am on two motorcycles. On the way back they stopped at a convenience store to buy a telephone card and argued with a group of teens outside the store. As soon as they left, they were chased by three other teens who started firing at them.
Tew, No and Petch were at the same night-time venue as the victims that night to celebrate a friend's birthday. They left at about 3am. Ms Nuttha said police based their case on little more than that evidence.
CCTV footage showed three suspects riding on a motorcycle on Liang Muang Road where the shooting took place. Police initially could not find the gun used in the incident, saying at the time that the suspects probably threw it into a swamp.
Upon further investigation, the charges were dropped. Their case was one of countless throughout the Kingdom in which innocent people are charged, put in jail and forced to admit to crimes they haven't committed. Some are lucky enough to prove themselves innocent quickly, while others spend years trying to do so yet are never able to clear their names.
But even those who are able to prove their innocence are stigmatised by society, a scar that will remain for the rest of their lives.
Chuvit Kamolvisit, the founder of and MP for the Rak Thailand Party, who helped Ms Nuttha fight for compensation after the truth was revealed, said No and Petch were brought to a "safe house" where they were beaten up by police and forced to confess. Both were terrified and, in desperation, confessed to the crimes.
Petch told his mother that if he had not confessed, he could have died. "I would definitely not be able to go home," he told her.
Soon after news of the arrest was made public, Ms Nuttha and her family were bombarded with messages on online social media sites and from her own neighbours.
She said she could barely walk into her neighbourhood fresh market without being harassed. One vendor called her son "a very bad boy" and said she should not sell her vegetables to his family.
One neighbour among a group passing by Ms Nuttha's house asked her, "If your son didn't do anything wrong, why did the police arrest him?" Another asked: "Are all of your family members vicious people?" Someone else said: "We shouldn't mix with this family. They are all murderers."
Ms Nuttha said she could not eat properly during the 10 days her son remained in custody. Her head was filled with her son's questions: "Mum, when will I be released?" and "Mum, I have to appear before court, right? The police don't believe what we told them _ will the court listen to us?"
Ms Nuttha worked tirelessly to get her son and nephews out of prison. She lodged a petition with opposition MPs, contacted the media and consulted a lawyer, but her efforts bore no fruit.
Both mother and son were fraught with nerves. For Tew, staying at the Juvenile Observation and Protection Centre without knowing what was happening was "torture".
"I was so scared when I was detained there. The seniors there all know when they will leave the place but I had no idea when they would let me go. I really had no hope when I was there," Tew told Spectrum.
Eventually, however, the tide turned and the police found the actual assailants _ a discovery they made by mere chance. On July 20, two men and one teen were arrested for murdering a police officer who had attempted to arrest them for possessing illegal drugs on July 9. Upon further investigation into that case, police found that the bullet casings in the policeman's murder indicated that they came from the same gun that was used in the July 10 student shooting.
The three arrested in the policeman's killing confessed that following his murder they went to the same night-time entertainment venue as the students, got into a quarrel with them and later shot them.
Tew found out on July 20 that he could go home. He was immensely relieved.
"I felt as if a big stone has been lifted from my chest," he said.
He may have been free, but returning to school and society was another story. Tew lost his confidence and was too shy to go to school.
His mother said he did not dare to leave the house.
As examinations approached, Ms Nuttha urged her boy to go to school but he replied: "What can I do, mum? I really don't want to go."
Although his school's headmaster made an official announcement to all students that Tew was innocent, the boy's mental scars have yet to heal. He feels better now, but still refrains from going out at night and occasionally has nightmares.
A defendant in a criminal case who is proved innocent is entitled to receive government compensation. An officer at the Justice Ministry's Rights and Liberties Protection Department said that each year the department receives an average of 5,000-6,000 compensation demands per year, but only 300 to 400 are usually approved. The compensation amount is small _ victims receive 200 baht for each day they were detained and another 200 baht a day to compensate them for lost work time. Compensation is only paid when there is a court order for the suspects to be held in custody.
Mr Chuvit said that while the three boys in this case received a total of 200,000 baht in compensation from a police fund for people who are unfairly arrested and detained, other "scapegoats" receive far less. He cited the case of a taxi driver who was given 20,000 baht after being wrongly arrested for raping and robbing 16 passengers.
Wanchai Sornsiri, secretary-general of the Senate's Committee on Human Rights, Rights and Liberties and Consumer Protection, pointed out that there are many factors that lead to police making improper arrests.
Mr Wanchai, a trained lawyer with 30 years of experience in the justice system, said that when a criminal case falls under the spotlight the pressure is intense for police _ from both their supervisors and citizens _ to make an arrest. Also poor and undereducated people are likelier to be the victims of false arrests because they do not know their rights, do not have enough money to hire a capable lawyer or "do not know a big guy".
Patipol Argars, a lawyer who has helped many innocent victims, said the legal system promotes inequality. The experience and ability of the lawyers in a case may factor more strongly into a verdict than the quality of the evidence. This makes skilled legal representation of paramount importance _ and often it is a luxury poor people cannot afford.
"The standard of our lawyers must be urgently improved as lawyers provided for free by the court usually lack experience," he said.
Police officers' conduct is also often questionable, said Sarawut Sukban, a lawyer. He said police often fail to enforce the law effectively. In cases where juveniles become suspects, a social worker or a psychologist should be required to witness the interrogation.
"The problem lies with improper enforcement and compliance with the law by the authorities," Mr Sarawut said.
To stop the cycle of innocent people being railroaded for crimes they didn't commit, Mr Wanchai said both police and the general public must change. "Police need to change the way they operate, which is often not in compliance with the law. The police and society as a whole should also adjust their attitudes towards the accused to ensure that they are considered innocent until proven guilty."