Teen died after 'determined assault'
This story contains graphic content.
Hayden Miles most likely died from bleeding to the brain after a "prolonged and determined" assault, causing him to slip into a coma and die, a pathologist says.
John Gavin Gosnell, 28, is accused of killing and dismembering the body of 15-year-old Hayden and burying his remains in three locations.
He denies murder, saying the killing was manslaughter.
The Crown wrapped up its case this afternoon with evidence from forensic pathologist Martin Sage, who examined Hayden's dismembered remains and carried out an autopsy on the various parts on December 17, 2011.
Sage had "no doubt" that Hayden was already dead when his body was dismembered.
Because of the decomposition of the brain and soft tissue in the 17 weeks between the death and the autopsy, it was impossible to determine the exact cause of death.
Instead, Sage relied on witness statements to determine the most likely cause.
He found Hayden suffered significant injuries to his head and face.
The assault was sufficiently prolonged and Hayden survived long enough to develop "spectacular" facial swelling, he said.
By the time he was put on the couch he was showing abnormal breathing patterns, and was either already unconscious or close to it.
From this, Sage concluded Hayden most likely died from an acute subdural brain haemorrhage, consistent with descriptions of a "prolonged and determined" assault by Gosnell, resulting in loss of consciousness and then death.
The only fractures found on Hayden's skeleton were a nasal fracture, showing he had a broken nose, and another to his right forearm.
The fractures, which showed no sign of healing, could be explained through an assault using fists, kicks or a blunt instrument, or a fall, or during burial.
Sage said the "spectacular" swelling described by two men who saw Hayden's body on the couch on the morning of August 23, 2011, meant he remained alive for several hours after the beating.
Swelling did not occur after death.
Other contributors or causes could have included traumatic brain injury causing his brain to swell, which could also lead to coma and then death.
His position lying on the couch could have compromised his airway, which could have been further obstructed by a bleeding nose.
Sage believed Hayden would have already been unconscious when placed on the couch on August 22, or lost consciousness shortly after.
The decomposition meant an exact time of death could not be established. The remains from the graves showed they came from a slightly built, relatively short European youth.
Dental records and fingerprints showed the remains, which all matched, came from Hayden.
Gosnell had forced his girlfriend to assault Hayden as the boy sat naked, bleeding and unable to defend himself in the shower, the trial was told earlier.
Gosnell told police during a filmed interview on December 14, 2011, that it was only after the shower that the assault on the 15-year-old stopped.
He had already punched, kicked and "twisted" the boy's body while he screamed in pain.
He then took Hayden into the kitchen for a drink, and then walked him to the shower to get cleaned up.
Once there, Gosnell resumed the assault.
Gosnell told police he felt angry at Hayden and wanted to "hurt him" and "make him to feel what I was feeling".
He took a razor blade and cut and scratched him, trying to make Hayden do it to himself.
Gosnell also called for his then partner, Nicolette Vaux-Phillips, to assault Hayden.
He placed a cloth or towel over Hayden so he could not see, then "made her kick him".
"She wasn't into it, but I told her to do it."
He told her: "This is what happens to people who talk s..."
Gosnell said he wanted her to assault Hayden because she needed to stand up for herself.
He said earlier that Hayden had told Vaux-Phillips that Gosnell was "using her for money".
This comment sparked Gosnell's fatal assault.
Gosnell sat forward with his head facing the floor during the video.
The murder trial resumed this afternoon after being adjourned when a juror started crying.
The court has been watching details of a videoed police interview where Gosnell revealed disturbing details of how he dismembered the Christchurch teenager.
A female juror began crying, as well as members of the public in the gallery.
Justice Chisholm called for an immediate 15-minute break, extended to 1.45pm.
It was the first emotion seen from the jury, which had remained composed throughout the week.
The jury this morning heard that Gosnell used a 20-centimetre kitchen knife to cut up the boy's body after finding him dead on the morning of August 23, 2011. He had beaten him up the previous night.
He told Detective James Haigh he usually used the knife to cut bread.
Gosnell also used an electric jigsaw he had bought in May of that year. He said the jigsaw cost $20 and took blades about 5cm long.
The blade he used to dismember Hayden's body fell out a couple of times and he would use an Allen key to put it back in, he said.
The jigsaw had spare blades but he did not use them.
The knife and the blades were later burnt in a fire in the backyard.
Yesterday, the court heard that Gosnell had told police he had worked as a prostitute "for a laugh".
He told police that his clients were "strictly ladies". They included married women and they would "go for lunch".
He said he wanted to try prostitution while he was in Dunedin to see if it would work, "and it did".
As the trial continued yesterday, Gosnell described not being able to stop beating Hayden but that he never wanted to kill him.
Police conducted three filmed interviews with Gosnell in late 2011.
Initially, he stuck to his cover story, saying Hayden had turned up at the flat intoxicated, badly beaten and, Gosnell believed, wanting to confess his love for Gosnell's partner, Nicolette Vaux-Phillips.
Gosnell helped him have a shower, put him to bed on the couch, and he was gone in the morning.
By the second interview on December 11, police had seized bloodied carpet from the flat and interviewed witnesses who arrived there on the morning of August 23.
One described Gosnell coming out with blood on his arms and hands and a sound like that of a vacuum cleaner coming from inside.
Gosnell told them he had "given someone a hiding" the previous night.
The person was now dead, so he was "cutting him up and was going to bury him around Christchurch".
It was only after police charged Gosnell with murder that he agreed to a "truthful" account.
In the third interview, he said Hayden had arrived at his house after being assaulted and robbed of an iPod and cellphone by Gosnell's friend.
Hayden told Vaux-Phillips that Gosnell was using her for money, "and I snapped".
"I went out there and beat him up. He tried to leave. I didn't let him leave. I took him inside. Give him another hiding," he said
Vaux-Phillips told him "that was enough" - "but I couldn't stop".
He put Hayden in the shower, where the beating continued.
Eventually, he "snapped out of it", put Hayden on the couch and went to bed.
Finding him dead the next day, he "couldn't believe it".
"I didn't want to kill him."
He sought help from an associate, who said Gosnell needed to kill Vaux-Phillips as well, but "I couldn't kill two".
He got a tarpaulin, put Hayden's body on it, got a knife and "started chopping him up".
He buried parts of Hayden's body in two cemeteries and his organs in the backyard. He then "burnt everything".
Gosnell and Vaux-Phillips decided to go to Dunedin, where he had previously worked as a male prostitute.
On August 25, they burgled a house and caught a shuttle bus south.
More of the interview will be played today. The trial is expected to last two more weeks.