The death of former MMA fighter Blas Avena -- who last fought War Machine at Bellator 96 -- is being investigated as a suicide ... Las Vegas Metro Police tell TMZ Sports.
32-year-old Avena was found dead around 11:36 AM Wednesday morning in his Las Vegas apartment.
A spokesman for the LVMPD tells us, "Arriving police and medical personnel located an adult male who was pronounced deceased at the scene. As of now, the death is being investigated as a suicide."
We're told an autopsy took place earlier this week -- but officials won't name an official cause of death until further tests are completed.