The men who stole ¥384 million from a Tokyo gold buyer last week in Fukuoka likely timed the robbery to coincide on a day he would be withdrawing the cash alone, investigative sources said Monday.

The man, who works at a precious metals shop in Tokyo, was robbed Thursday and had also withdrawn a large sum from the same Mizuho Bank branch with another person the previous day, the sources said.

He had used the same branch in the past to make large withdrawals on his own, they said, and the robbers probably knew the company had low security.

The man told police he arrived in Fukuoka on April 18 to purchase gold bullion and was attacked Thursday afternoon by two men who sprayed him with something and snatched a carry-on bag containing the cash while he was returning to his vehicle from the bank.

The attackers fled in a white van that used side roads in an apparent attempt to avoid the license plate monitoring system on major roads and expressways, the police found.

The van bore a stolen license plate and the police believe it has not left the prefecture, the sources said.

During the investigation, a group of South Korean men were stopped at Fukuoka airport on the same day as the robbery for trying to take a huge amount of cash out of Japan undeclared.

Investigators now believe it is less likely these men were involved because they were carrying more money than the amount stolen and the cash did not have the victim's fingerprints on it.

The Koreans were arrested anyway on suspicion of violating the customs law by not declaring the cash.