Source in Tripoli confirmed to The Tripoli Post that Senussi arrived Wednesday. He's in the hands of security forces while he awaits trial for alleged crimes against the Libyan people, the Post reports.
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.
"The extradition of Senussi sends a message to the remnants of the pro-Gadhafi elements who are now outside Libya that they will be hunted down and brought back to face justice in Libya," the report adds.
The French government sentenced the intelligence leader to life in prison in absentia for his role in the downing of a commercial airliner over Niger in the 1980s.
The government in Mauritania agreed to extradite Senussi after convicting him of entering the country illegally, The Wall Street Journal reports. Mauritania had said it would send him back to Libya under certain conditions, but offered few specifics about the arrangement Wednesday.
The ICC told the Journal it had no official word of the transfer. The government in Tripoli maintains the right to try former regime officials in its national courts.