Deputy national police chief, Pol Maj Gen Chalermkiart Srivorakhan, said that reports that Panya Yingdang had already been arrested were not true.
Police investigators were dispatched to track down the prime suspect along the Thai-Cambodian border, Maj Gen Chalermkiart said. They had not caught him yet.
Commander of the Crime Suppression Division, Pol Maj Gen Maitree Chimcherd, said police had information that Panya was hiding in a village in Cambodia.
Cambodian authorities have been asked to help arrest him, the CSD commander said.
Maj Gen Chalermkiart and Maj Gen Maitree were speaking after two more suspects in the murder of Paweena Namuangrak, 20, and her friend Anantachai Jitram, 21, surrendered to police.
Kritsana Sisuk, 22, and alleged gunman Narong Warintharawet, 22, turned themselves in separately to local police in Nakhon Sri Thammarat yesterday night (Aug 6) and were then taken to Sattahip Police Station in Chonburi and charged.
The two arrests brought the number of the suspects held in the fatal shooting of Miss Paweena and Mr Anantachai, in the parking lot of Khao Chee Chan (Buddha Mountain) in Sattahip on July 29 to five.
The three others are Kiatisak Suransaengmilboon, 35, Sayant Sisuk, 43, and Jirasak Unaiban, 34.
Lt Col Thaweesak Suethong, deputy superintendent at Satthahip Police Station, took Kritsana to the crime scene at Khao Chee Chan for a re-enactment this morning.
The suspect said he accompanied Phuket nightclub operator Panya, the alleged mastermind, to Chonburi because he thought the man wanted to patch up his relationship with Ms Paweena.