A former California fire battalion chief has been found guilty of second-degree murder in the slaying of his girlfriend.

The Sacramento County jury reached the verdict Wednesday in the case against Orville Fleming, one day after his 57th birthday. He could face 15 years to life in prison when sentenced.

Fleming was charged with murder in May 2014 after 26-year-old Sarah June Douglas was found dead in their south Sacramento home.

Flemings' attorney argued that he was guilty of the lesser crime of manslaughter. Fleming testified that the couple argued the night of her death and that he felt like a zombie as he grabbed a knife to stab her.

Fleming's arrest triggered a months-long investigation into the California Department of Forestry and Fire Protection's training academy that led to firings and demotions.