CARACAS, Venezuela - (UPI) - Cuban exile leader Orlando Bosch and three co-defendants were arraigned Monday on first-degree murder charges in the Oct. 6 sabotage bombing of a Cuban airliner which killed 73 persons.

For security reasons, Criminal Court Judge Delia Estaba Morena chose a room at political police headquarters to read the charges to the defendants.

The session was boycotted by defense attorneys, who received depositions against their clients and said they will appeal the arraignment procedure.

Bosch, underground leader of the anti-Castro United Revolutionary Organizing Committee, and private detective Luis Pasada Carriles were charged with conspiracy in the bombing.

Venezuelan photographers Freddy Lugo and Hernan Ricardo Lozano were named as "material authors." They were aboard the aircraft at one point but got off at one of its stops before it crashed near Barbados.

Bosch has admitted knowing Ricardo Lozano, an employee of Posada's private detective agency. Posada, a naturalized Venezuelan and a former commissioner in the political police, also is a Cuban exile.