From the article:
“Poirot solves the mystery of the protagonist’s killings in the novel, (but) Lady Garnett’s murder remains unsolved till date. She lurks through its rooms at night whispering, looking for her murderer. Many visitors have found their room doors open. Some claim to have seen her apparition walk through the corridors. Visitors who confronted her said that she checked them thoroughly before dissolving. The hotel shut down for many years until it was acquired and renovated by ITC Welcome Group Hotels in 2009.”
Ghosts of Bengal 