The dead man was identified as Cedric McWiden who had earlier been involved in a high speed car chase with police.
Jiwaka police commander Joseph Tondop said McWiden had not cooperated with the police when stopped and was cautioned for speeding.
He and gone to his Kugark village, got some of his tribesmen and followed the police to Minj police station where an argument followed.
When the Highway Patrol, which had confronted McWiden earlier, headed for their base in Kudjip, the villagers blocked the road at Kugark and waited there for them.
Since they were outnumbered the three policemen fired into the air to disperse the crowd.
McWiden and three others were arrested and locked up at the police cells in Banz where he was found dead the next morning.
Angry relatives, claiming that he was the victim of police brutality, have now blocked the Highlands Highway in three different locations between Kurumul and Minj, interrupting traffic flow.
Police have appealed to the relatives to remove the blockade within 24 hours.
Police commander Tondop said McWiden had died in police custody and the circumstances surrounding his death would be thoroughly investigated.
“If the investigations reveal that he died from police injuries, those responsible will face the full force of the law,” Superintendent Tondop said after suspending the five members of Highway Patrol unit, pending investigations.