Two hotel employees -- Raj Theekoy and Abinash Treebhoowoon -- both confessed to their part in her murder on the island last Monday.
But the third man -- Sandip Moneea -- has made no such confession.
Investigating officers said they did not question him yesterday but plan to do so this week.
Inspector Ranjit Jokhoo said they have been in touch with his counsel and are planning to record a statement shortly.
Referring to reports that the murder charge could be downgraded to that of unlawful killing, he said they were continuing to build information in the case.
"We have been continuing our investigation into this case and are verifying the information," he said.
"We have a charge of murder but the investigation has to be continued to consolidate that charge.
"This is not an issue that the charge is going to be changed.
"For the time being the charge is murder and I am very sure that it (the final charge) will be murder."
Two of the men -- Mr Treebhoowoon and Mr Mooneea -- have been charged with murder.
They allegedly entered the room with the intention of stealing money from a purse that had been seen lying in the room, but killed Michaela when she returned to the room unexpectedly just two minutes after they had entered it.
The third man -- Mr Theekoy -- has been charged with conspiracy to murder as he allegedly passed by the room and heard Michaela scream and then saw two men leave the room acting suspiciously.
The families of all three men maintain their innocence.
Barrister Ravi Rutnah -- who is representing Mr Treebhoowoon -- is to seek an independent inquiry into the police investigation at their next court appearance tomorrow. Tomorrow's appearance is a procedural hearing but the three will be seeking bail at another appearance on February 2.
Mr Rutnah is to raise 21 separate issues which he says calls the investigation into question.
He said the police have refused a number of times to allow him to speak to his client, while a note was written on the board in the Major Crime Investigation Team (MCIT) offices stating: "Treebhoowoon be denied access to counsel."
In a letter which he has given to the Complaints Investigation Bureau he stated: "I am of the view that the inquiry is not being conducted in a professional manner and I urge upon you to investigate this incident as a matter of urgency."
Investigating officers have denied any allegations of police brutality or impropriety.
"What happened Michaela is very sad but it was an isolated incident," added Inspector Jokhoo.
You can leave of messages of condolence to the Harte and McAreavey families