Iranian officials have confirmed the deaths of 16 police officers who were abducted by Sunni militants in June.
The men were seized in south-east Iran by Jundullah group, which claims to represent the Baluch minority.
Three of the group were killed in June and the others were reportedly taken across the border into Pakistan.
Iranian police patrol the long border with Pakistan and suffer regular casualties in the battle against drug smugglers, say correspondents.
The BBC's Jon Leyne in Tehran says Jundullah, or Army of God, is engaged in a mixture of political violence and drug smuggling in the often lawless region.
The group seized the men from a checkpoint in Saravan, Sistan-Baluchestan province, and demanded the release of 200 of its members from Iranian prisons.
Soon afterwards, Arabic news channel al-Arabiya showed footage of three of the police officers being killed by the militants.
On Thursday, deputy police commander Ahmad Reza Radan said that investigations by the government, intelligence authorities and police had now shown that "all of our loved ones have been martyred by Jundullah terrorists".
Mr Radan said the authorities were investigating how to retrieve the men's bodies.
Sistan-Baluchestan province borders both Afghanistan and Pakistan and has a history of banditry and kidnappings, say correspondents.
It is one of the poorest regions of Iran and one of the main routes for smuggling drugs from Afghanistan to Europe.