Ravi Rutnah, who is representing 31-year-old Avinash Treebhoowoon, said he was withdrawing from the case in response to remarks made in court by a chief inspector.
During his testimony, the policeman made a series of claims against Mr Rutnah.
He said he was late arriving for a meeting with his client two days after the murder last January and later shared food - fried rice - with police officers.
Mr Rutnah said he had been subject to an accusatory attack on his professional integrity.
"As a direct consequence of that, I have decided to withdraw representing accused number one," he said.
Before leaving, he declared he would be back - like Arnold Schwarzenegger, and it is understood he now wants be a witness in the trial.
The judge adjourned the trial for the day after the defence tendered a list of additional witnesses on the back of the shock development.
UTV's Alison Fleming said: "Whether or not Ravi Rutnah will take the stand as witness remains to be seen."
Mr Rutnah told her: "It is a matter for the interpretation of the court whether the court will accept me giving evidence or not."
It's not unusual in circumstances like these for a barrister to give evidence as to what took place during interviews and thereafter.
It came after the court heard a detailed confession signed by Treebhoowoon in the presence of his defence lawyer, in which he admitted killing Mrs McAreavey.
In the statement, Treebhoowoon said his co-accused told him they must kill the honeymooner after she walked in as they tried to steal from her.
He explained how he saw a purse containing a lot of notes in room 1025 and decided to steal it.
Treebhoowoon checked if the coast was clear before going back into the room, where he saw Sandip Moneea and told him about the purse.
His statement said: "I heard someone opening the door and then I saw a young lady entering.
"She started to scream: 'What are you doing? Why are you searching in my pocket?'
"I pushed her and she fell, but was not injured. Sandip and I grabbed her," the statement read.
"I caught hold of her leg and Sandip caught her at the neck for her to stop screaming.
"She was struggling. She fell unconscious but was breathing."
The statement went on to explain how they put Michaela's body in the bath and turned on the tap to get rid of the evidence.
Treebhoowoon said in his statement how they didn't take money from the purse after that, and added: "She was not dead, but Sandip said we had to kill her because she saw us.
"I had no reason to kill her; it was only because she saw us."
Before he signed his statement, Treebhoowoon said: "I regret what has happened."
"And I ask forgiveness for that."
Treebhoowoon has since claimed the confession was forced out of him, and along with co-accused Moneea denies murdering the 27-year-old teacher in the Legends resort in 2011.
The Chief Inspector was asked about another statement, already heard by the court, relating to claims of police brutality.
The policeman said it was "totally false". "There was never any violence used against the suspects," he said.