The former officer, identified as Eric D., will be be questioned again over arms-trafficking charges, Radio France Internationale reported.
"The weapon used in the crime has not been found, nor has the motorcycle helmet on the identikit picture, nor has the motorbike described by several witnesses and sought by investigators, so the inquiry continues," Annecy prosecutor Eric Maillaud told reporters on Friday.
Marc Dufour, a lawyer representing Eric D., said his client was "shaken" by his detention.
"When you take a close look at his movements he couldn't have been at the scene of the crime in the time needed," he said.
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