Prosecuting counsel Michael Bowman told the jury that Bobby Ryan's death was "violent and brutal", his body stripped naked and hidden in an underground tank after a "callous, calculated, controlled murder".
But the prosecution could not identify a specific weapon, a time or a precise location of death. Mr Bowman said Mr Ryan left Mary Lowry's farmhouse at 6.30am on 3 June 2011 and his body was found 22 months later, less than 60 yards away.
The pathologist who carried out the post-mortem examination suggested death was from blunt force trauma either from an assault or being hit by a vehicle. But Dr Khalid Jaber was not available to give evidence to the trial so instead his report was reviewed by Professor Jack Crane a former state pathologist for Northern Ireland.
Using Dr Jaber's report and photographs from the post mortem Professor Crane identified fractures to Mr Ryan's head, nine of his ribs and his thigh bone. The level of decomposition was consistent with death "some time" earlier and it was "entirely plausible" that he died on or about 3 June 2011 - the date he went missing.
He said Mr Ryan had sustained "severe head injuries", consistent to blows to the head with a blunt object or as a result of being crushed or compressed. These would have caused bleeding and damage to the brain causing death.
The rib fractures could have been caused by a blow to the back or by falling into the tank, Professor Crane said.
The fracture to the thigh bone, the strongest bone in the body, was consistent with a heavy blow from a bat. He said it was possible but unlikely that the leg injury was caused by a fall into the tank.
He noted a suggestion that the injuries could have been caused by a motor vehicle collision but Professor Crane said: "While this is possible there is no real evidence to support this."
He said the combination of injuries was not consistent with a vehicle impact. Usually, he said, leg injuries caused by vehicle impacts occur below the knee, although he accepted that the height of the victim and other factors would have to be taken into account. He also noted that pedestrians struck by cars usually suffer a single head impact when they hit the ground, which would not cause multiple fractures to the skull as seen in this case.
During cross-examination, Professor Crane said the injuries sustained by Mr Ryan would have resulted in significant bleeding. If a weapon was used he would expect to see cast-off blood patterns over the wider area and pooling of blood where the body lay.
Dr Michael Curtis was called by defence counsel Lorcan Staines SC. He told Mr Staines that in 2015 he and his colleagues, including Professor Marie Cassidy, reviewed the post mortem report carried out by Dr Khalid Jaber in 2013. Looking at the post mortem and photos of the body, Dr Curtis said he was in "total agreement" with Dr Jaber that the cause of death was blunt force trauma to the head.
He added that in his opinion the most likely mechanism for those injuries was "vehicular impact trauma, that is, a person being struck by a moving vehicle". He added that this was his opinion and there are other possibilities, including the use of a baton or baseball bat.
He explained the presence of multiple fractures to the skull by saying that when a pedestrian is struck by a vehicle the head can strike the vehicle and then the ground or anything else in the area.
Under cross-examination by the prosecution, Dr Curtis agreed that any of the injuries to Mr Ryan's head could have caused immediate unconsciousness. Mr Bowman suggested that the removal of Mr Ryan's clothes and personal effects suggested that the person responsible knew something about the limitations of forensic evidence. Dr Curtis agreed. He also agreed that any vehicle that caused those injuries to Mr Ryan would have suffered "significant damage", most likely to the windscreen or the roof.
