The death of Omran Shaaban, who had been hospitalized in France, raised the prospect of even more violence and score-settling, with the newly elected National Congress authorizing police and the army to use force if necessary to apprehend those who abducted the 22-year-old and three companions in July near the town of Bani Walid.

Shaaban was praised as a "dutiful martyr" by the National Congress, although his family says he never received a promised reward of 1 million Libyan dinars ($800,000) for capturing Gadhafi on Oct. 20, 2011, in the former leader's hometown of Sirte. The eccentric dictator was killed later that day by revolutionary fighters.

The Libyan government said it would honor Shaaban with a funeral befitting a hero. His body was greeted at the airport in his hometown of Misrata by more than 10,000 people for a procession to a soccer stadium for funeral prayers.

Photos on social media websites showed a wooden coffin with a glass window that revealed Shaaban's face, with white gauze covering his head.

In the capital of Tripoli, several hundred protesters gathered outside the headquarters of the National Congress to demand that the government avenge Shaaban's death.