Thursday, November 5, 1998 Published at 18:01 GMT
Colombian drug lord killed in prison
Herrera surrendered himself to the police two years ago
A man posing as a lawyer entered a maximum security prison in Colombia and killed one of the jailed leaders of the now defunct Cali drugs cartel.
Fellow prisoners jumped on the man and beat him unconscious.
Herrera was one of the top five leaders of the Cali gang, which once controlled some 80% of the world's cocaine trade.
Correspondents say the motive for his murder was not immediately clear.
His seven year sentence was doubled last October in light of new evidence.
The United States had requested the extradition of Herrera, but Colombia's extradition law only affects crimes committed after the law passed, in December of 1997.
American authorities accuse Herrera of having exported more than 3,000 kilos of cocaine to the United States.
The government of President Ernesto Samper put all of the chiefs of the Cali drugs cartel behind bars.
But shortly after Mr Samper took office in 1994, it was revealed that the cartel had made a $6m contribution to his presidential campaign.