Chile's ex-secret police chief Gen Manuel Contreras has begun a 12-year jail sentence over the disappearance of a left-wing activist in 1975.
There were ugly scenes as Contreras emerged from court
Contreras' relatives fought the police as he was arrested at his home.
Later, demonstrators pelted him with eggs as he arrived at court and when he left on the way to prison.
Human rights campaigners see his jailing as a crucial victory because he played a leading role in the early years of military rule.
There were extraordinary scenes at the Supreme Court in the capital, Santiago, as Manuel Contreras was rushed inside under heavy police protection.
Hundreds of demonstrators had gathered to celebrate his detention and pelted him with insults, eggs and plastic bottles, says Clinton Porteous in Chile.
There was more chaos when he left the court and again when he was delivered to prison.
Body not found
Miguel Angel Sandoval, a member of the Movement of the Revolutionary Left, vanished after he was arrested by secret police agents in January 1975.
His body has never been found.
Four other former members of the secret police were also jailed in connection with the disappearance.
The general has already been jailed once, over the killing of a former Chilean foreign minister, Orlando Letelier, in Washington in 1976.
Thousands of supporters of the previous government were killed, tortured or forced into exile during the rule of Gen Augusto Pinochet's 1973-1990 military rule.
Contreras set up the unit that played a key role in the early years of repression of the military government.
Gen Pinochet himself faces charges of human rights abuses, including kidnapping and murder.