Round and Watson were walking along the path in opposite directions, the court heard, and a study of CCTV footage from each access point to the canal “found no sign that anyone else came or went from it during the relevant period”.
Williams told the jury: “As you will have gathered, Darren Round was not seen again until his body was found hours later, floating in the water.
“We will come to details of the injuries which Round had sustained but, in short, they included facial fractures, two rib fractures, a fracture of a bone in his neck, and significant damage to his brain.
“He was most likely still alive when he went into the water, though he may well have lost consciousness at or about the time he fell in.”
The victim died from a combination of immersion and blunt force trauma, Williams said.
He told the court: “We the prosecution say Round had been subjected to a serious assault involving a number of heavy blows to his face and chest, and his neck either being struck hard or more likely placed under severe, sustained pressure.”
Watson was interviewed by police in June 2021 after being identified by two people, including a police officer, following a media appeal in March of the same year.
He told police he knew nothing about the incident in which the 48-year-old had died, disputed that the man caught on CCTV was him and claimed he was “probably in pigeon park” , the grounds of Birmingham’s St Philip’s Cathedral – at the relevant time.
In May 2024, Watson was interviewed again and denied having ever met Round, the court heard.
Further forensic work concluded that the defendant’s DNA was present on the inside surface of the victim’s left, front, jacket pocket, Williams said.
He also told jurors it was understood that Watson now accepts he “had an altercation with Round on the canal path and struck him repeatedly”.
Williams said: “We understand it will be proposed that he – Mr Watson – was attacked by Round first and he only used reasonable force to defend himself.
“There may also be a dispute about whether he caused all of Round’s injuries or, indeed, his death.
“And it may be claimed that Round not only was conscious but shouting aggressively when he, the defendant, fled the scene.”
The trial continues.