Jack Steven James Brearley, 24, says prosecutors have it wrong and he didn't strike Cassius Turvey in the head with a metal pole in Perth's eastern suburbs on October 13, 2022.
He has told a jury his co-accused, Brodie Lee Palmer, 29, swung the blows that led to the 15-year-old Noongar Yamatji boy's death in hospital 10 days later.
Brearley's girlfriend at the time, Aleesha Louise Gilmore, 23, and one of his co-workers Mitchell Colin Forth, 26, are also on trial, charged with murdering Cassius.
Brearley said Palmer threatened him after the incident and said he would end up in a body bag if he spoke about it.
Under cross-examination by prosecutor Ben Stanwix, Brearley on Thursday agreed he told police he spotted a neighbour near the alleged murder scene with a weapon that could have been a piece of pipe or a machete.
"You knew Cassius was dead by then?," Mr Stanwix asked.
"Yeah," replied Brearley.
He agreed that he knew he was being interviewed as a suspect over the death, and that "pointing a finger" at the man would implicate him in the murder of a child.
Mr Stanwix: You said that to blame (the man) for Cassius's death ... And you knew (the man) had nothing to do with the incident and was innocent?
Brearley: Yeah.
Mr Stanwix: So you tried to frame an innocent man for the murder of a child?
Brearley: Yeah.
Mr Stanwix: Isn't it the case that you will tell any lie imaginable if it gives you a prospect of getting away with what you did?
Brearley: No.
Brearley said he did it to protect himself, Palmer and Gilmore.
He agreed he had previously said Palmer threatened to kill him if he was implicated in the alleged incident.
Mr Stanwix also accused Brearley of choosing the man because he was of a similar height and build, and had been in the area on the day Cassius was allegedly attacked.
Brearley agreed he looked similar but denied that it was why he named the man or that he would "point the finger anywhere" if it took the blame off him.
During the at-times terse cross-examination on his fifth day in the witness box, Brearley also agreed he, Palmer and Forth gathered weapons before Cassius was injured and that they went looking for a group of youths he said had threatened to "run through" the home he shared with Gilmore.
He also agreed that he and Palmer re-enacted the attack on Cassius a day after the alleged incident, which was recorded on CCTV.
But he has consistently said he only punched Cassius after the teen slashed him with a knife.
Prosecutors allege Brearley chased Cassius down and deliberately struck him in the head with a metal shopping trolley pole while he was "hunting for kids" because somebody had smashed his car windows.
The trial continues.
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