Macchie solari (1975)

Simona Sana is a young pathologist whom works in a morgue in Rome, Italy which gets with with a wave of violent suicides which are attributed to a summer heat wave. Driven to exhaustion from the intense heat and the long hours worked, Simona struggles to complete her college theses about natural deaths when one suicide victim is brought in the morgue in which a young Catholic priest named Paul Lenox who identifies the corpse as his sister, but that did not commit suicide, but was murdered and set up to look like a suicide. Simona teams up with Father Lenox to solve the mystery and stay one step ahead of a mysterious killer who now begins to stalk her when Simona gets a little too close to the truth of the suicides.