Read more about the killing of Russian girls in Thailand here
Anuchit Lamlert was arrested Thursday and has confessed to the murders of Tatiana Tsimfer, 30, and Liubov Svirkova, 25, whose bodies were found Feb. 24 slumped in lounge chairs on a beach in Pattaya.
Anuchit told police the motive for the killings was robbery and that he killed the pair because he was "afraid they would remember my face."
However, police believe he may be lying.
"There are inconsistencies in his confession and the evidence," Police Chief Gen. Seriphisut Temiyawej said. "I believe the murder is linked to a crime organization and there may be other people behind it."
Seriphisut also said authorities were investigating why the two women came to Thailand.
Pattaya, a popular destination for Russian tourists, is known for its beaches, thriving sex industry and high crime rate.
Local police are under heavy pressure to solve the murder amid a campaign to improve the city's battered image, the AP wrote.
Authorities released a sketch of Anuchit ahead of his arrest and conducted an intense search for the motorcycle shown in the surveillance video from the murder scene.
Along with Anuchit, police have arrested a second suspect Tinnakorn Meeklee who sold him the gun.
"It is time to clean up the crime and deal with mafia gangs that are deeply rooted in Pattaya," Seriphisut said to a group of about 300 business men and hotel operators who came to greet him before he left to investigate the suspect.
Seriphisut was appointed to the top police job earlier this month after his predecessor, police Gen. Kowit Watana was dismissed from the post by Prime Minister Surayud Chulanont following a failure to solve a series of deadly New Year's Eve bombings.
Police yesterday found the murder weapon used in killing two Russian women in Pattaya on February 24.