By Jack Queen and Jan Wolfe

NEW YORK, Jan 5 (Reuters) - Shackled at the ankles and dressed in prison garb, toppled Venezuelan President Nicolas Maduro stood before a U.S. judge on Monday and declared he was still his country's rightful leader as he faced charges that could put him behind bars for life.

“I am innocent. I am not guilty. I am a decent man. I am still president of my country,” Maduro said through an interpreter, his voice rising before Judge Alvin Hellerstein cut him off.

The 63-year-old, captured days earlier in a dramatic U.S. military raid, wore orange slippers, beige pants and layered black and orange shirts. He scribbled notes on a legal pad while lawyers discussed what promises to be a bruising legal fight.

He faces four U.S. federal criminal counts that include narco-terrorism conspiracy, cocaine importation conspiracy and possession of machine guns and destructive devices. Each charge carries a maximum sentence of life in prison.

His lawyer Barry Pollack told Hellerstein that he expects extensive litigation over the legality of Maduro's "military abduction."

Maduro's wife Cilia Flores also pleaded not guilty. She faces the same charges except for narco-terrorism. The next court date was set for March 17. 

The U.S. has deemed Maduro an illegitimate dictator since he declared victory in a 2018 election marred by allegations of massive irregularities. His capture marks Washington's most controversial intervention in Latin America since the invasion of Panama 37 years ago.

Two groups of protesters — supporters of Maduro and those backing his ouster — argued outside the courthouse on Monday.

“We are outraged at what the U.S. has done to the head, the duly-elected head of Venezuela," said Sherry Finkelman, 80, a retired teacher.

Alejandro Rojas, a 51-year-old data scientist who moved to the U.S. from Venezuela in 2017, said he hoped to return soon with Maduro gone.

“It's so emotional, just being able to reconnect with family, being able to have a country back again," Rojas said.

Maduro was first indicted in 2020 as part of a long-running narcotics trafficking case against Venezuelan officials and Colombian guerrillas. He was being held at a Brooklyn jail with a troubled history.

In a new indictment unsealed on Saturday, prosecutors allege that Maduro is the kingpin of a cartel of Venezuelan officials that has partnered with some of the world's most violent and prolific drug trafficking groups, including Mexico’s Sinaloa and Zetas cartels, the Colombian paramilitary group FARC and the Venezuelan gang Tren de Aragua. 

"As Venezuela's President and now de-facto ruler, Maduro allows cocaine-fueled corruption to flourish for his own benefit, for the benefit of members of his ruling regime, and for the benefit of his family members," according to the indictment filed by prosecutors from the U.S. Attorney's Office in the Southern District of New York.

Prosecutors allege that as president, Maduro directed cocaine trafficking routes, used the military to protect shipments, sheltered violent trafficking groups and used presidential facilities to move drugs. 

Legal experts said prosecutors will need to show evidence of Maduro's direct involvement in drug trafficking to secure a conviction, which could prove difficult if he insulated himself from decision-making. 

(Reporting by Jack Queen and Maria Tsvetkova in New York; Additional reporting by Jan Wolfe and Tom Hals; Editing by Noeleen Walder and Howard Goller)