>> reporter: chilling, new details what investigators believe happened inside that washington, d.c., mansion. sources telling nbc station wrc that savos savopoulos, his wife, 10-year-old son and longtime housekeeper were held captive in the home overnight. and they were bound and threatened through thursday afternoon when they were murdered their multimillion dollar home set on fire. this, as we're hearing from a second housekeeper, who may have been among the last people contacted by the savopouloses. >> a lovely family. very nice family. >> reporter: nellie, who asked her face not be shown, says mr. savopoulos left her a voice message the night before the fire, telling her not to come to work the next day and to contact figueroa's husband. >> they say, i hope you can get this message, my wife sick my son is sick, and vera offered to stay overnight but her phone is