The Narcotics Suppression Bureau (NSB) is digging deeper into a drug-trafficking scandal that allegedly points directly to a highway police officer.
The agency believes that other officers might have been involved in a scheme to traffic drugs from Laos to buyers in southern Thailand.
"He could not have done it alone," NSB chief Pol Lt Gen Sommai Kongwisaisook said on Thursday, referring to Pol Lt Col Thanakrit Nitsaphan.
- Earlier report: Highway cop suspected of aiding wife's drug trafficking
The anti-drug agency is collecting evidence, expanding the investigation in order to find out whether other police officers were part of the gang, he added.
Pol Lt Col Thanakrit was found in a house raided by the NSB and Khlong Luang police in Khlong Luang district in Pathum Thani on Tuesday. The operation followed the earlier arrest of his wife, Thip-arpha Raksasaengalong - a suspected ringleader of the gang - in Udon Thani.
Pol Lt Col Thanakrit was transferred from Division 8 of the Highway Police unit to the Central Investigation Bureau on Wednesday. Later in the day, he was placed on involuntary leave by national police chief Pol Gen Chakthip Chaijinda.
Police alleged that the highway policeman had given his wife information about which roads could be used to avoid detection when sending drugs, mainly marijuana, from Laos to Songkhla via Nong Khai.
He denied all allegations but the NSB chief was confident that the evidence was sufficient to prosecute him.
The highway police officer also collaborated with his wife on money transactions and vehicles used to deliver drugs, Pol Lt Gen Sommai alleged, saying that following Pol Lt Col Thanakrit's arrest, he moved two million baht in cash from the raided house to a location in Phetchaburi.
Pol Gen Chakthip on Thursday gave investigators the green light to hunt down other corrupt police officers, saying that cops found to have links with illicit drugs will have nowhere to hide.
The apprehension of Ms Thip-arpha was part of a drug crackdown in 59 locations across the country. She was linked to one of four gangs targeted by authorities during the eight-day campaign that ended last Friday.
During the campaign, police seized 3.6 million methamphetamine pills, two kilogrammes of "ice", 770 grammes of cocaine, 21 pistols, 11 vehicles, 21 plots of land, a number of condominiums, almost 8 million baht in cash and a quantity of gold - altogether worth around 910 million baht.