A two part movie on TV with a bad cop- I think it was in the 90's He was either a bad cop or killed a cop and took uniform, so people trusted him. Remember a log cabin, large dogs. Every time you thought the kidnapped people were going to get help, the bad guy killed the people that might have helped the victims. I think the people tried to get away in a winnebago!

What you are describing sounds a lot like Dean Koontz's Intensity (1997), starring John C. McGinley. I seem to remember him dressing as a cop or security guard uniform and he does kill people who attempt to help. The majority of the movie takes place at the house. The character does have a bunch of trained german shepherds and the girls attempt to get away in his winnebago type vehicle. If it isn't the one you are thinking of, you should rent the movie. McGinley does an amazing job as a psychopathic killer.

Intensity (1997) (TV) (http://www.imdb.com/title/tt0118350/)