Rivas, who currently resides in Australia, defended DINA's torture practices as a "necessary tactic" to coerce leftist militants to reveal their plans and association with others in the struggle against the fascist dictatorship The former Brigada Lautaro agent stated that Pinochet was "a good president" and disassociated herself from the fate of Chile's desaparecidos, adding that the years spent working as a DINA agent were the best years of her youth.
At the age of 20, Rivas joined the Ministry of Defence, taking up a secretarial role. in 1974 she joined DINA after taking instruction in military intelligence and was incorporated in the infamous Brigada Lautaro - organised by Manuel Contreras to provide protection for influential officers within DINA. The brigade was later entrusted with clandestine operations relating to the detention, torture and extermination of MIR and Communist Party militants, operating secretly at Cuartel Simon Bolivar, also described as the place where no one got out alive. The existence of the extermination centre was revealed by Jorgelino Vergara Bravo, whose testimony as narrated to Chilean investigative author Javier Rebolledo included torture practices, the administration of cyanide injections prior to the disposal of bodies, the packaging and disappearance of bodies, mock executions, sarin gas experiments by Michael Townley which were witnessed by various DINA officials, looting, organ trafficking in coordination with Colonia Dignidad, and the degradation inflicted upon detainees as they begged to be murdered in order to avoid systematic and incessant torture.
Rivas has been living in Australia since 1978. Her return to Chile in 2006 to celebrate her niece's wedding resulted in her indictment by Chilean courts for her role in Calle Conferencia. Following her release on bail, Rivas was aided by a friend in absconding from Chile and returned to Australia via Argentina.