The women, Tatiana Tsimfer, 30, and Lyubov Svirkova, 25, were shot at point blank range on the beach at a sea resort near Pattaya last Saturday. Police detained a 24-year-old local suspect Thursday.
"There are inconsistencies in his testimony," acting police chief of Thailand, Seriphisut Temiyawej, told businessmen and hotel managers of Pattaya.
Thailand's eastern seaboard resort of Jomthien near Pattaya is located about 70 miles southeast of Bangkok and is very popular with Russian tourists.
"I am sure the murder is connected to an organized crime group and there might be other people behind the man," the police chief said.
The suspect, Anuchit Lamlert, who has already confessed to having committed the murder, insists his goal was to rob the women. He said he had shot them dead because they were yelling and screaming. Lamlert already has a criminal record for robbery against foreigners, police said.
Police are now searching for a suspected paymaster of the murder. A Bangkok-based newspaper, The Nation, has said a woman is suspected of having ordered the murder out of jealousy with her Russian-born husband, a local businessman.
The Nation paper said Saturday the weapon used in the killing had been found Friday.
"The 9mm Chinese-made Norinco pistol was found in a pond pinpointed by a witness, who is a close friend of murder suspect Anuchit Lamlert and volunteered information to police about the weapon Friday," the paper said.
The women were buried in their home city of Kemerovo, Siberia, Friday.
