Ex-commerce minister Chaiya Sasomsap said former national sports shooter Jakkrit Panichpatikum visited him days before he was murdered on Saturday night.
Mr Chaiya said Jakkrit visited him at his home in Nakhon Pathom early last week to discuss his problems.
The former national sport shooter, accompanied by a man identified only as Lek, did not seek any help from him, the former commerce minister said.
Rumours have circulated that Jakkrit visited Mr Chaiya to seek his protection.
Mr Chaiya said Jakkrit told him some 30-40 million baht he had kept in a bank vault had been withdrawn by his wife while he was detained by police recently following a family quarrel.
Jakkrit had planned to sue his wife, but Mr Chaiya said he tried to convince him not to do so.
Jakkrit, 40, was attacked in a drive-by shooting by two men on a motorcycle while driving his black Porsche near Ramkhamhaeng Soi 166 in Min Buri district on Saturday night. The pillion rider fired several bullets through the driver's window, hitting Jakkrit three times.
Jakkrit's maid, who was also in the car, sustained wounds to her leg from broken glass. Both were taken to Serisuk Hospital. Jakkrit died on the way to the hospital.
Police are looking into possible motives for the murder, including a conflict over a Buddha amulet purchase.
Mr Chaiya said Jakkrit told him he had many Buddha amulets and had taken photos of his amulets and diamond-studded cases containing them. However, his amulets and other items had been taken away by his wife, the former commerce minister quoted Jakkrit as saying.
He insisted Jakkrit did not mention any conflict over a Buddha amulet sale. Only general issues, including his family problems, were discussed, he said.
He said he only knew that Jakkrit was a national sport shooter with an interest in Buddha amulets.
Pol Maj Gen Thitirat Nongharnpitak, deputy chief of the Metropolitan Police Bureau, said police had examined closed-circuit camera footage from the scene of the murder and believed the attack was well-planned. Investigators will ask a motorcycle expert to examine the CCTV footage to identify the model used by the attackers, Pol Maj Gen Thitirat said.