Lawyers for the former prime minister of Libya say he is in danger because of the many secrets he knows about Moammar Gadhafi's regime.
Al-Baghdadi al-Mahmoudi was convicted of illegally crossing into Tunisia and imprisoned but the conviction was overturned.
Tunisian authorities have continued to hold him, however, following an extradition request from the Libyans.
With Gadhafi's death, he is the "sole holder of the secrets of inside the state and relations between Libya and certain powers," said Mabrouk Korchid, the coordinator for the prime minister's 50-strong legal team.
The lawyer added that the 70-year-old was weak and suffered from diabetes.
Gadhafi and his son were captured by rebels after the fall of Sirte, but died shortly afterwards.