Former intelligence official Abu Zeid Omar Dorda was charged Tuesday in a Tripoli court with mobilizing security forces to fire on civilian demonstrators during an uprising that eventually led to NATO intervention and the October death of longtime leader Moammar Gadhafi.
His brother, Abdullah, told the BBC the charges were warrantless.
"All these things they're saying about him are not true," he said. "My brother is one of the Libyan people who looks out for his country, for its people and its safety."
Dorda was once said to be one of the staunchest Gadhafi supporters, appearing on state television in April 2011 to say it was "impossible" for him to consider defecting.
He was arrested in September.
Military intelligence chief Abduallah al-Senussi was captured in Mauritania in November. Saif al-Islam Gadhafi, Moammar Gadhafi's son, is in Libyan custody. Both men are wanted by the International Criminal Court on charges of committing crimes against humanity during last year's civil war.