Former Legends Resort employee Rajiv Bhujun had accompanied the victim's husband, John McAreavey, to let him into his hotel room when he went to look for his missing wife and tragically found her dead in the bathtub.
Prosecutors had planned to call him as a witness, but senior police officer Inspector Sunilduth Nucchedy confirmed in court on Tuesday that Mr Bhujun's whereabouts were unknown.
His last port of call was said to have been Dubai.
Further DNA evidence was also heard during the latest court session, after the jury previously heard there was no such link to either of the accused - Avinash Treebhoowoon, 30, or 42-year-old Sandip Moneea.
But a potential match was identified with another hotel employee, Dassen Naraynen.
English expert Susan Woodroffe said DNA which could be Naraynen's was found on a key card for the hotel room and on a cupboard in the suite, but she stressed it could be a chance observation in the results.
Naraynen was appearing at a different court on the island on Tuesday, facing a provisional charge of conspiracy to commit larceny - he had previously been facing a conspiracy to murder charge, but that was dropped.
His case was adjourned until August.
Witnesses are asked questions by the prosecution, then they have to go through three defence barristers and then possibly back to the prosecution - this is why it's taking such a long time.
UTV’s Alison Fleming
As the DNA evidence was heard, laughter again broke out in the courtroom - despite previous concerns over the inappropriate handling of proceedings.
This time, Michaela's sister-in-law Claire McAreavey asked the people sitting behind her to be quiet.
During Inspector Nucchedy's testimony, he was asked by defence lawyers for both accused if he was aware that a hotel guest had left the resort unexpectedly at 11.45pm on the day of the murder.
"I can't say if there was any premature departure," he replied.
Michaela was found dead shortly after having lunch with her husband by the hotel's pool - it's the prosecution's case that she caught the accused stealing from their honeymoon suite when she went to get some biscuits.
Inspector Nucchedy further told the court that any reference to her husband as "a suspect" in police logs made in the hours after her death may have been made in error.
He insisted that he had not identified any suspects at that stage in the case and that he didn't know why the word had been mentioned in reference to John McAreavey.
The officer further explained that reference to a police sentry outside the room occupied by the widower after the murder meant that an officer had been sent to fulfil victim support duties.
Given that he (John McAreavey) is a foreigner and he just lost his wife in a murder case, it could be that the police could be of assistance.
Inspector Sunilduth Nucchedy
Another policeman, Constable Hans Rouwan Seevathian, denied in court on Tuesday that he had beaten and threatened one of the accused.
The court heard the allegation that the officer had warned Treebhoowoon: "If you don't do what I tell you, I will beat you up again and you know how it's going to be. Listen well, you keep that in your mind."
But he told the judge, Mr Justice Prithviraj Fecknah: "No, my lord - I never said those words to the accused party, my lord."
Treebhoowoon and Moneea deny the premeditated murder of Michaela at the luxury Legends Hotel last January.
The Supreme Court also heard that a former suspect, who is now a witness for the prosecution - fellow hotel worker Raj Theekoy - did not originally tell police he saw the two accused emerge from the crime scene.
He now claims he heard female cries from the room where Mrs McAreavey was killed and shortly after saw Treebhoowoon and Moneea exit the door, but none of those details were in his signed police statement.
In the statement, he simply said: "I did not kill the lady. I don't know how she was killed. I don't know anything about the lady."
Mr Theekoy, who was originally charged with conspiracy to murder before the charges were dropped, provided no further details about the murder at that time.
UTV's reporter in Mauritius, Alison Fleming, said 40 witnesses still have to give evidence and the court is hearing from around two per day.
John McAreavey was not present in court, as he is expected to give evidence next week.
"I would be very surprised if we do hear from him this week. In fact, it's looking like it will be towards the end of next week," Alison said.