Is there a way to approach someone, maybe initially push into own apartment, but then, under some threat of a knife or other weapon, guide her to an elevator, downstairs and out through the back door? Or follow her to the garage car and (if their apartments were close, then perhaps the cars stood close, too?) push to get into his car? There may be a dead space in the garage camera. He could have taken her somewhere close by. Why I don’t think she was in apartment? To conceal a body for 3 days is not something bloodhounds would miss.