The only info I could find were the following ships begining a cruise of 16 Sep 09 -
Regent (Radisson) Seven Seas Mariner - Departing Anchorage (Seward), Alaska
Costa Cruises Costa Classica - Departing Shanghai, China
Holland America Rotterdam VI - Departing Rotterdam, Holland
Holland America Eurodam - Departing New York City, New York
Costa Cruises Costa Atlantica - Departing Savona, Italy
Carnival Cruises Carnival Victory - Departing Bridgetown, Barbados
Sea Dream Yacht Club SeaDream II - Departing Venice, Italy
Carnival Cruises Carnival Spirit - Departing Vancouver, Canada
MSC Cruises MSC Orchestra - Departing Genoa, Italy
Holland America Noordam - Departing Rome (Civitavecchia), Italy
Costa Cruises Costa Europ - Departing Savona, Italy
Azamara Cruises Azamara Quest - Departing Venice, Italy
Princess Cruises Island Princess - Departing San Francisco, California
Hurtigruten Cruises Nordlys - Departing Bergen, Norway
Hurtigruten Cruises Lofoten - Departing Kirkenes, Norway
Of these, I'm guessing that Carnival's Spirit would be the most likely candidate .... Carnival does a lot of theme cruises and charters for various intrest groups, and what would be more apporpriate than the "Spirit"?
Gook luck on your ghost hunt .....