Philippe Verdon's supporters say his ill health may have contributed to the decision to kill him, Radio France International reported Friday.
Al-Qaida in the Islamic Mahgreb (AQIM), which has claimed responsibility for Verdon's abduction, says he was killed in retaliation for France's military intervention in Mali. An autopsy said the manner of Verdon's death was similar to that often used by AQIM.
Pascal Lupart, chair of a support committee, said Verdon, 53, might have been killed because he was "really ill."
Verdon suffered from an ulcer and an abnormally fast heartbeat. Lupart speculated Verdon was killed because he was unable to travel quickly as AQIM fled the French advance into northern Mali.
Verdon and a colleague, Serge Lazarevic, were taken from a hotel in northwestern Mali in November 2011.
The status of Lazarevic is unknown.