Andrew Gittins and Michelle Swayne, both 41, were unanimously convicted of the murder of Kevin Childs at his flat in Park Lodge Lane, Eastmoor, Wakefield, on February 6.
Mr Childs, 58, was beaten, bound and gagged. His face had been scratched with a fork and a sock was later found stuffed in his mouth.
He had suffered more than 60 separate injuries.
But his death was not initially treated as suspicious by a police officer who attended the scene.
As a result of the police officer’s conclusion, Mr Child’s body was taken to a mortuary at Pinderfields hospital, Wakefield, where it was to wait its turn for a standard post-mortem examination.
A pathologist noticed a sock in Mr Child’s mouth and decided that a standard post-mortem was not appropriate.
As a result a Home Office approved forensic consultant pathologist was contacted to conduct a full post mortem.
The pathologist found that the sock was deep within Mr Child’s mouth and had compressed the tongue to the back of the mouth.
Three of his teeth had also been knocked out.
There was also bruising, abrasions and other injuries to the head, face, inside the mouth and both arms and legs. Swayne and Gittins were both arrested on February 18 but denied murder.
Leeds Crown Court heard how the homeless and alcoholic couple had turned up at the victim’s home on the night of the murder and asked to stay.
Gittins claimed he was asleep during the attack and knew nothing.
Mother-of-six Swayne later told police she had seen Gittins battering Mr Childs after he had walked in on the couple when they were in bed.
She admitted punching and kicking the victim, placing the sock in his mouth and scratching his face with a fork but denied intending to kill him or cause him serious bodily harm.
But the pair were found guilty by the jury of six women and four men after a two-week trial. Gittins and Swayne will be sentenced at a later date but the Recorder of Leeds Judge Peter Collier said he was duty bound by law to impose a life sentence.