Preston Crown Court heard that 19-year-old Nathan Richardson had taken a cocktail of drink and drugs at a New Year’s Eve house party before he had a “chance encounter” with 67-year-old Wenqing Xu, who was going for a morning jog.
Francis McEntee, prosecuting, said Mr Xu, who was from China but had been staying with his daughter Diana in Preston since last summer, was left with 28 areas of injuries to his head and neck following the unprovoked attack, as well as a laceration and bruising to his genital area.
He said the motive for the assault remained a mystery.
Richardson was seen dragging the pensioner, who weighed just 7st 12lb, along the street but ran off when he was disturbed by witnesses shortly before 8.30am.
Mr Xu was found near Plunginton Community Centre in Preston, barely alive and wearing only a T-shirt which was pulled over his chest.
He died in hospital later that morning.
Sentencing Richardson to life imprisonment, Judge Mark Brown said Mr Xu had been in “the wrong place at the wrong time”.
He said: “The precise circumstances of the encounter are not clear but there is no doubt that you attacked him in a brutal, vicious and very cruel way.
“He was subjected to a sustained and callous assault to his head and neck and I am satisfied he suffered additional degradation when you removed his lower clothing and dragged him along the street.
“You were seen to be struggling with what was thought to be a roll of carpet, which you were pulling along the street. In fact it was Mr Xu.”
He said Richardson left his victim “dying in the gutter”.
The court heard that after the attack Richardson, of no fixed address, went to the house of friend Luke Jenkinson, 22, on nearby De Lacy Street, where he changed and washed his clothes.
He later made admissions over messages and in person to friends and family, and messaged one contact saying he had “f***ed some chink up”.
Mr McEntee said friends had reported Richardson telling them he had “kicked and stamped” on Mr Xu’s head and pulled his trousers down and pulled him by his genitals, although he later denied that.
They described him laughing and “buzzing off it” as he made the admissions.
The court heard Mr Xu’s wife and daughter, who were in court for the sentencing, had felt unable to complete a victim personal statement.
Judge Brown said: “Such is the stress that this family have found it difficult to put into words the impact of his death upon them, but it is clear to me from Mrs Xu, as she is present in court and the distress written on her face, that the impact upon her and her daughter simply cannot be calculated.”
John Jones QC, representing Richardson, said he was “a young man with the most disadvantaged background and upbringing” who had been diagnosed with a personality disorder and learning difficulties.
Mr Jones said: “He has pleaded guilty to the murder of an entirely innocent and respectable man. This has affected the defendant profoundly and he is sorry for what he has done.”
Jenkinson was sentenced to two years and nine months after admitting assisting an offender. The court heard he did not know Richardson had murdered Mr Xu when he helped him.