Hi Stephen,
Here is the itinerary for day 13, it does not include a visit to the killing fields:
Visits will be made to the Royal Palace complex and the impressive Silver Pagoda. Then you will continue on to the National Museum, where you can view Angkorian and Pre-Angkorian sculptures. You will pass the waterfront cafés and restaurants. Next you will have the opportunity to climb the hill to Wat Phnom, the city's main temple.
Thanks,
Vickie