A man on trial for murder says he cut another man's throat because he feared his co-accused who had already bashed and repeatedly stabbed the victim would do the same to him.
Luke James Hutchings told the jury he believed the victim was already dead when he slashed his throat.
Hutchings, 30, was giving evidence on Thursday in the South Australian Supreme Court.
He and Michael Joseph Lindsay, 29, have pleaded not guilty to murdering Andrew Negre, 37, whose dumped body was found in an Adelaide reserve on April 8, 2011 about a week after he died.
The court has heard that after drinking at a hotel, Mr Negre was part of a group that went back to Lindsay's house.
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Hutchings told the jury it all went wrong after Mr Negre offered to pay Lindsay $200 for sex.
Hutchings said he went to another room after seeing Lindsay repeatedly punch Mr Negre and bang his head on the floor.
When he returned, he saw Lindsay grab a knife and repeatedly stab Mr Negre whose trousers were no longer on him.
"I just stood there like everyone else," he said.
Hutchings said Lindsay then looked up at him while holding the knife.
"I took the knife out of his hand ... I cut across Andrew Negre's throat," he said.
Asked why, Hutchings replied: "I thought maybe he might want to do it again and come after me".
He said he was scared of Lindsay and was the only person in the house not related to him.
"I was frightened and thought I had better do something or he could retaliate."
When Hutchings slit his throat, Mr Negre had not been moving and appeared to be dead.
Hutchings said he helped clean up the scene and move the body into a wheelie bin after Lindsay told him "to get rid of this mess".
Under cross-examination, Hutchings denied underplaying his own role.
He also denied egging on Lindsay and holding the victim's legs, so Lindsay could go through his pockets.
The trial is continuing.
