The 12 were charged with murder following last month's lynching of Mohammed Msallem, an Egyptian living in the southeastern mountain village of Ketermaya, who was suspected of killing an elderly couple and their two young granddaughters.
When Lebanese police brought him to the scene of the crime a day after the murder, angry villagers overwhelmed the policemen, beat Msallem with sticks and stones and stabbed him.
To cheers and applause, they stripped him to his underwear and socks, paraded him through the street and hoisted him up on an electricity pole with a butcher's hook.
Lebanese troops eventually arrived and took away his corpse.
Human Rights Watch had called on Lebanese authorities to prosecute the perpetrators and said nothing justifies mobs taking the law into their own hands.
Many of the villagers were unrepentant while others said authorities had to bear some responsibility for sending the suspect out in public with only a few policemen.
Security sources said Msallem had confessed to the crime but his motive was not clear.
