A man accused of murdering his wife and four in-laws in Uttaradit allegedly also swindled almost 30 million baht from a priest who served as the rector of a Catholic college in Chon Buri.
Police looking into the origins of Teerapon Pinanon's wealth found he stands accused of duping Chaiyo Kitsakul, 66, a priest he had known for several years, into lending him 29.86 million baht to help clear a case involving the sale of land in Phuket.
The money was never repaid and Mr Teerapon did not own the land, according to a police complaint filed by the priest.
Mr Teerapon, 37, was arrested in Kra Buri district of Ranong near the Myanmar border on Tuesday morning by a team of police and soldiers after fleeing Uttaradit.
His mother-in-law, Namphueng Kingkaew, and her two elder sisters, Nampha and Kanokwan Inthasit, were shot dead on Sunday at a house in Phichai district in Uttaradit.
Mr Teerapon's wife, Kanyarat Kingkaew, and his father-in-law, Wirat Kingkaew, were killed shortly after at another house nearby.
Two other men were also wounded at the second house.
The suspect was released from jail after serving time for drug offences before he met his wife. Witnesses told police he told his wife he had made a lot of money investing in stocks.
Police learned Mr Teerapon had driven to see the 66-year-old priest at Darasamut School in Sri Racha district, Chon Buri, last year.
Mr Teerapon allegedly told the priest he had sold land he owned in Phuket, about 10 rai, for 35 million baht, but the money had been frozen by authorities because his relatives faced drug charges.
Mr Teerapon produced land documents in his name and persuaded Mr Chaiyo to lend him 29.3 million baht. When he was due to pay back the money, Mr Teerapon kept postponing payment and then disappeared.
Alarmed, the priest checked with the Phuket land office, which told him Mr Teerapon was not the owner of the land he claimed to have sold.
The priest then filed a complaint with Sri Racha police, accusing Mr Teerapon of swindling him out of the money, the reports said.
In Uttaradit yesterday, police made Mr Teerapon re-enact his alleged crime.
Pol Col Thapset Khuenkaew, chief investigator of Uttaradit, said the re-enactment took place at the provincial police office instead of tambon Phayaman in Phichai district, where the murders occurred, because police feared the victims' relatives and friends would attack him.