Satnam Singh, 74, was found with serious injuries in a Derby street in July 2015 - opposite the Sikh temple where he volunteered.
Police initially thought he had been hit by a car but last year arrested 30-year-old Sukhraj Atwal for murder.
Mr Atwal denies the charge. His defence said there was a lack of "real evidence" and witnesses.
The prosecution has previously alleged Mr Singh - the defendant's former step-grandfather - was "brutally assaulted" over a long-running family dispute.
The trial at Nottingham Crown Court claimed Mr Atwal repeatedly stamped and jumped on Mr Singh in the early hours of 23 July.
The victim was found with 41 fractures to his ribs, lacerations to his heart, a fractured skull and severe brain damage.
The attack itself was not captured on CCTV but Mr Atwal's car was seen entering and leaving the area shortly before Mr Singh was found.
Defending barrister Shaun Smith, said the case was based on "half-baked theories" and "speculation".
"There is no footage of what happened," he added.
"There are no eye witnesses and when it comes to real evidence there's nothing.
"Nothing to place him at the scene on his footwear or his car, no-one to hear or see it [the attack], or hear cries of distress or see anyone run into a car."
He said although the victim and defendant lived just streets apart "they ignored and blanked one another" and "barely knew" each other.
Mr Atwal chose not to give evidence in court.
The trial continues.
The trial of a man accused of murdering a pensioner in the street has heard he "had no motive" to kill him.