The couple then went back inside but did not reappear. After waiting two hours, the taxi driver contacted hotel staff who checked the couple's room and found there was nobody there. The taxi then went to a nearby police station where the luggage was examined.
On Wednesday, the hotel refused to comment. A spokesman said the resort was cooperating with police. "There is no more information at this stage. An investigation is proceeding," said the spokesman, who asked not to be named.
Police said Mrs Mack's daughter and Mr Schaefer had been detained in another hotel in the Legian area of the island. Col Djoko Hari Utomo, the police chief in Bali's capital, Denpasar, told the Associated Press they were studying CCTV footage that had been provided to them by the hotel. He said that the footage showed Mrs Mack having an argument with Mr Schaefer in the hotel lobby on Monday.
Another senior police officer, Gede Redastra, told the Jakarta Post, that after loading the luggage into the taxi, Ms Mack and Mr Schaefer had left the hotel without checking-out.
"We suspect that Tommy and Heather are a couple and that they are the perpetrators," said Mr Redastra. "Tommy and the victim had a fight last night in the hotel lobby."
Is it understood Mrs Mack was a member of the Caxton Club, a historical and literary society based in Chicago. In an interview last year with the club's magazine, Mrs Mack said that after leaving university, where she had studied political science, she had worked for Senator Kennedy as a researcher.
She later returned to college to complete a PhD at the University of Chicago under the direction of the novelist Saul Bellow, who died in 2005. "It was an extraordinary time," she told the magazine. "We studied the books Bellow wanted to study, which included the authors Joyce, Fitzgerald, Dickens, and Balzac. Of course, I also read all of his own books, but we never discussed them."
Mrs Mack was married to the composer and arranger James Mack. He died in 2006. He had worked on more than 60 albums for artists including Nancy Wilson and Jerry Butler.
- UK Independent