An 86-year-old man has been charged with murder in the death of his 78-year-old wife, who was found dead at the bottom of a staircase in their Queens home, cops said. 

Luz Porras had suffered trauma to her face, and was unconscious and unresponsive Wednesday night when found at the base of the first-floor stairs at the home she shared with her husband Ovido Porras on 91st Street near 91st Avenue in Woodhaven, cops said.  

Her husband was at home when cops arrived around 8:20 p.m., and was initially taken into custody for questioning by investigators. He was charged with murder 24 hours later, police said. 

He also faces raps for tampering with physical evidence and criminal contempt, cops said. 

Police could not confirm exactly how the woman was killed, and are awaiting information from the city Medical Examiner’s office.