At first glance, it looked like the Klong Toey shooting on Oct 11 was a revenge attack between technical students who study at rival vocational colleges but when the police team of the Metropolitan Police Bureau dug deep, they found the shooter and his partner were part of a crime syndicate comprised of at least 84 members.
"It was organised crime. We believe about 10 people were involved. They have teams to plan, monitor students from the rival school, survey the area, help them escape, give legal advice and even finance their crimes," Pol Maj Gen Theeradej Thamsuthee, commander of the MPB's Investigation Division, told the Bangkok Post in an exclusive interview.
Pol Maj Gen Theeradej is leading the investigation into the incident near the Sacred Heart Convent School on Sunthon Kosa Road, where two men opened fire on a group of students amid an argument.
One shot missed the intended target and struck Sirada Sinprasert, a 45-year-old teacher queuing up to use a bank's ATM on Sunthon Kosa Road.
Sirada, who taught at the school, died at the scene, while Thanasorn Hongsawat, 19, the target, was severely wounded and died later in hospital.
According to Pol Maj Gen Theeradej, the gang's activities extend beyond just inter-school rivalry as it also trains young students or former students to be killers.
"At least 84 people were identified as being members of the network. Police are considering who to arrest, and will target the network's financiers," said Pol Maj Gen Theeradej.
Officers specialising in drug-related crime are also helping to track down the financial sources behind the network.
After reviewing footage from more than 1,000 CCTV cameras in the vicinity, the two suspects were spotted lifting their motorcycle onto a cargo van before it was driven to another location.
The bike was later spotted in another part of the country having been repainted from red to blue.
Police received reports that the repainting occurred in an abandoned area of bushland on the outskirts of Ayutthaya's Bang Sai district following the discovery of discarded blue and red spray paint canisters.
Pol Maj Gen Theeradej instructed his team to review old cases of shootings between the two technical colleges which led them to send a team to a house that a group of technical college students rented in Wong Sawang Soi 19 in Bangkok's Pracha Chuen area.
After putting the soi under surveillance, officers spotted the cargo van, along with a sedan and other motorcycles belonging to the suspected killers and were able to identify a further five suspects they believed were involved.
Armed with arrest warrants, police raided six locations, including the house in Wong Sawang 19, an apartment in Bangkok's Rong Muang area, and houses in Pathum Thani and Nonthaburi, two weeks after the shooting.
In total, police rounded up eight individuals, all aged 20-23 years old. Some had records of involvement in other shootings, including the death of a vocational student of Uthenthawai killed near the Faculty of Pharmaceutical Sciences building of Chulalongkorn University in January this year.
Theeradej: Hunting gang's financiers
Another one was linked to a shooting spree at the wedding of an alumna of Uthenthawai in Bangkok in August last year which left one dead and four injured. All denied any involvement,
"They gave us the same answer that 'They don't know. They were not involved' and kept their mouths shut," he said.
The shooter and the motorcycle rider are still at large.
Pol Maj Gen Theeradej said his team found the rented house in Wong Sawang Soi 19 was a base for the gang. Police called it a "safe house" where senior students brainwashed juniors into killing students from rival schools.
"The training had levels starting from basic to advanced including learning how to track targets," added Pol Maj Gen Theeradej.
Police also found a picture of a Pathumwan student shot dead in April which "They used to stimulate hate and revenge".
Line group chat logs in which gang members congratulated the killers were confiscated during a police raid, along with uniforms, the cargo van, memory cards, two "ping-pong" explosives, and mobile phones.
Officers also discovered a .38 handgun bullet case inside the van, but no gun.
The rider is also believed to be of a higher rank because it was he who ordered the shooter to fire more shots at victims, he said.
"The gang even has its own ranks and uses symbols to show their position. We found several of the suspects had brandings made by metal gears on their bodies. One had four such scars on his arm which we believe represents the top rank," he said.
"This is no longer just fighting between rival institutions, but a crime organisation comprised of both former and current students," he said.
Pol Maj Gen Theeradej says further arrests will follow and the gang and its donors will be brought to justice.
Contact Crime Track: crimetrack@bangkokpost.co.th