Officers also searched the grounds outside in a bid to find possible forensic evidence left at the crime scene.
A murder probe was launched after 21-year-old Tom Bell was gunned down at the Maple Tree pub in Balby on Thursday night.
He was shot in his chest and abdomen in what detectives are treating as a targeted attack.
A gun was fired into the pub through the windows before the gunman fled the scene in a getaway car.
Detectives arrested a 29-year-old man on suspicion of murder over the weekend, with the suspect still in custody this morning.
A 21-year-old woman arrested on suspicion of assisting an offender was released from custody under investigation.
Tom was a popular professional boxer, who won all six of his bouts.
Friends and relatives gathered outside the pub over the weekend to leave flowers and console each other.
They also took part in a ‘justice walk’ from his former gym – the Doncaster Plant Works Amateur Boxing Club – to the Maple Tree pub.
Organisers said the event was aimed at honouring Tom and to send out a message that ‘gun and knife crime will not be tolerated’.
Tom’s mum, Tracy Langley, 51, was among those who took part.
Anyone with information should call South Yorkshire Police on 101 and quote incident 796 of January 17 or Crimestoppers, anonymously, on 0800 555111.