Six people were arrested Monday over the brazen gold bar heist perpetrated last July by men disguised as police officers on a street in the city of Fukuoka.
The Fukuoka Prefectural Police arrested the six in both Aichi Prefecture and Tokyo and sent them to Fukuoka.
It also found that the stolen gold was actually worth about ¥750 million, rather than ¥600 million ($5.4 million).
The Fukuoka police are pursuing other suspects, and the arrest total is expected to exceed 10.
According to investigative sources, a couple of men were approached by fake police officers in early July while transporting the bars in attache cases to a cash-for-gold store near JR Hakata Station. The bars weighed more than 100 kg.
The fake cops are suspected of taking the cases to a car and leaving after pretending to take them to a police department.
Earlier this year, police raided places associated with a man running jewelry shops on suspicion he aided the suspects to get cash for the gold bars.