[JURIST] A massive demonstration attended by thousands of people protesting the disappearance of Jorge Julio Lopez clogged the streets of Buenos Aires, Argentina [JURIST news archive] on Wednesday. The protest represents the third time such a demonstration has taken place since the 77-year-old witness went missing last month after testifying against a former police official sentenced [JURIST report] last month to life in prison for crimes committed during the country's Dirty War [GlobalSecurity backgrounder]. Human rights groups speculate that Lopez was kidnapped because he testified against Miguel Etchecolatz [Project Disappeared profile], the former chief investigator of the Buenos Aires province police. During the trial, Lopez said he had been kidnapped in 1976 and taken to a police station where he was tortured by Etchecolatz and other officers.

The government has offered a $60,000 reward for information about Lopez's disappearance. AP has more. BBC News has additional coverage.