Facing the largest anti-government protests in his 11 months in power, Venezuelan President Nicolas Maduro vowed to move forward with the prosecution of a leading opposition figure on charges of terrorism and murder.
Four anti-government protesters and one government supporter have died in clashes around the country.
The man the government blames for the deaths is Leopoldo Lopez, an opposition leader who turned himself in to authorities on Tuesday.
A court hearing to determine whether Lopez will be released or remain behind bars began inside a military prison Wednesday night, his family told CNN en Español.
Human rights groups warn about the danger of turning the protests into a persecution of political opponents.
The charges against Lopez, who has organized protests demanding better security, an end to shortages and protected freedom of speech, "smack of a politically motivated attempt to silence dissent in the country," Amnesty International said in a statement.
Human Rights Watch weighed in, too, warning that Venezuela must avoid "scapegoating" political opponents.
But the way forward seemed set, with Maduro referring to opposition leaders as fascists and vowing to take a hard line against those responsible for surging violence.
In a national television broadcast Wednesday night, Maduro accused the opposition of trying to overthrow his government with a slow-motion coup.
"This fascist group's leader is already prisoner. He will respond," Maduro said. "And I said, 'He will go to prison.' And that is what I did. And I will do that with all the fascists, wherever they are."
Charges against Lopez include murder, terrorism and arson in connection with the protests, according to his party, Popular Will.
Lopez denies the accusations, the party said in a statement, which also asked witnesses of the protests to send their own accounts of what happened to be used in his defense.
The party has blamed the government for the violence.
Court inside military prison
Crowds of supporters, media crews and security forces swarmed Venezuela's justice building as anticipation built over the hearing. But Lopez's legal team said Wednesday afternoon that officials had ordered a last-minute change of venue for security reasons.
Juan Carlos Gutierrez, an attorney representing Lopez, told reporters that a court had been set up inside the military prison outside Caracas where the opposition leader is being held. Defense attorneys were on the way to the prison and planned to argue against holding a hearing there, he said.
Lopez's supporters accused the government of violating his due process by setting up a court session inside the prison.
"This is unprecedented. Our constitution says that everyone should be judged in liberty," his father, also named Leopoldo Lopez, told CNN en Español on Wednesday.
Delsa Solorzano, a Venezuelan representative to the Latin American Parliament, said holding a court session inside the military prison raises a major red flag.
"It demonstrates that in Venezuela there is no separation of powers," she told CNN affiliate Globovision.
Lopez's wife, Lilian Tintori de Lopez, told CNN en Español she was holding out hope that her husband would be set free after the hearing.
"The last thing he said to me was for me to not forget what he is going through," she said. "Not forget that he is arrested for things that he has asked for: the liberation of political prisoners, liberation of students, no more oppression, no more violence."
Obama: Venezuela 'trying to distract from its own failings'
Major social and economic problems in Venezuela have fueled the protests. But as the demonstrations gained steam, officials have pointed fingers at other factors, accusing the United States of plotting to destabilize the government.
U.S. President Barack Obama fired back during a news conference in Mexico on Wednesday.