A couple were stoned to death for adultery in a remote area of Pakistan's western Baluchistan province, an official says, leading to six men being held on suspicion of murder.
The couple, both married to other people, were believed to be in their 30s, said Sarfaraz Bugti, the home minister for Baluchistan.
The woman's father and brother, and the man's uncle and father have been arrested, along with a cleric believed to have issued the order to kill them at the weekend. Another man linked to the cleric is also being held.
"It is a shameful act and the people involved in stoning the man and the woman will be brought to justice," said Bugti.
The woman's body would be exhumed for forensic examination on Tuesday, Bugti said. Authorities were still searching for the man's grave, he said.
Bugti said he ordered the local police chief in the couple's home village of Loralai to be dismissed for not taking action when the killings occurred.
In many rural areas of Pakistan, gatherings of tribal elders, often referred to as jirgas, issue death sentences for couples or women deemed to have offended the conservative culture. Such killings are illegal in Pakistan, but the police force is weak and often ignores them.
Even if the cases are brought to court, they can take years to be heard and the national conviction rate hovers between 5 to 10 per cent. If convicted, the victim's family can forgive the killers - a major loophole, since the killers often are the victim's family.
Women's rights group The Aurat Foundation says it tracks around 1000 cases of honour killings per year just from media reports. The true figure is probably much higher.
No one tracks the number of attempted or successful prosecutions.
In one high profile case that captivated the country, five women were allegedly killed in 2012 in remote Kohistan after they were videotaped singing and clapping softly to music with two men present.
The activist Supreme Court, which has championed human rights cases over the past five years, intervened in what was widely seen as a test case for women's rights.
But a botched investigation that ignored vital forensic evidence concluded the women were alive. Recently a lower court judge has taken up the case again after the women's alleged killers were convicted of three more murders.