After a six-week trial, prosecutor Bruno Sturlese branded Simbikangwa an "ethnic cleanser" who was "radically committed" to his work, and a "man capable of the worst" and demanded he be found guilty of genocide and not just complicity.
The former Rwandan army captain and intelligence director denies charges of crimes against humanity and complicity.
Simbikangwa told the Parisian court he did not participate in "the descent into chaos" in his homeland and minimised his role in the 100 days of bloodletting that killed some 800,000 minority Tutsis and moderate Hutus.
The defence was to take the floor on Thursday and was expected to question the reliability of prosecution witnesses.
The verdict is expected on Friday.
If sentenced to life, Simbikangwa, who was arrested in 2008 on the French Indian Ocean Island of Mayotte, faces a mandatory 22 years behind bars.
The trial is historic as it is the first in France dealing with the Rwandan genocide.
Rwanda has repeatedly accused France of having protecting those responsible for the massacres.
It follows similiar trials in Europe, including in Belgium, the Netherlands and Germany.