Iraqi security officials have discovered the bodies of 23 police volunteers kidnapped last Monday.
Attacks have not stemmed the flow of police volunteers
The men were found shot dead on open land north of the capital Baghdad, the officials said.
The victims were part of a group of 35 men seized by insurgents as they travelled home to the northern city of Samarra by bus last Monday evening.
They were returning home after they had failed to be accepted into a police training school.
Militants stopped the bus at a checkpoint. The men had received an armed escort on their way down to the capital, but not on their return.
The 12 other bodies are said to have been found last week.
The incident is the latest in a series in which insurgents have targeted recruits to the security forces.
In other developments:
- Four children and the brother of a policeman die when insurgents fire a rocket into the officer's house in Balad Ruz, north-east of Baghdad
- Four policemen are killed and nine injured in Baquba, north-east of the capital, when a roadside bomb targets their patrol
- A Jordanian kidnapped by militants demanding the release of a failed woman suicide bomber appeals for his life in a video.
The unrest continued as the Shia bloc that took the most votes in last month's election said it had begun moves to form a government of national unity.
IRAQ ELECTION FACTS
275-seat Council of Representatives will have four-year term
18 provinces are taken as separate constituencies
230 seats allocated according to population
45 seats distributed to parties whose ethnic, religious or political support is spread over more than one province
15 million eligible voters
One third of candidates in each party must be women
The United Iraqi Alliance has set up committees to hold talks with Kurdish and Sunni groups in the new parliament.
It says it will form a coalition with Sunni factions, but only if they do more to combat the insurgency.
The United Iraqi Alliance failed to win an absolute majority in December's vote and so must govern in a coalition.
The alliance took 128 of the 275 seats, Kurdish parties 53 and the main Sunni Arab bloc 44 in the 15 December poll.
Some Sunnis still allege poll fraud and may challenge the result.
However, the BBC's Jonny Dymond in Baghdad says there has been a flurry of positive feeling about the idea of a national unity government.
Many in Iraq believe that Sunni involvement in the political process could help bring an end to the violence which has racked the country since 2003, our correspondent says.