Niigata police arrested three people Friday on suspicion of killing a 44-year-old man last July to collect the payout from his insurance policy.
Koei Honda, 46, a former member of staff of an agricultural cooperative in the town of Yuzawa, Niigata Prefecture, was arrested, along with his two alleged accomplices.
The three are suspected of murdering Haruo Hayashi, former president of a defunct firm that managed water supply and drainage facilities, and making his death appear accidental, police said.
Hayashi held a co-op life insurance policy that paid benefits of 200 million yen in the event of accidental death.
According to police, Hayashi was found dead last July in the Nakatsu River in Tsunan, Niigata Prefecture. A car was found some 350 meters upstream.
The three allegedly killed Hayashi by forcing the car he was driving into the river.
Police initially thought he had died when the car accidentally plunged into the river but they later discovered inconsistencies that pointed to a possible murder.
Police discovered that lesions on Hayashi's body were minor compared with the extensive damage to the car, and later found that Hayashi had enrolled in the life insurance program, designating his company as the beneficiary.
They also learned that after Hayashi's company went bankrupt in April 1999 with debts of 200 million yen, Honda and two other suspects had repeatedly urged Hayashi to "repay the debts with insurance money."
The three suspects were indicted in February in a separate case in which they allegedly conspired with his acquaintances to steal about 27 million yen by making unauthorized computer operations.