Is it possible to do a Rigid Body chain that needs to split at a certain frame? Is it possible to have a Chain made of individual links that is being controlled by rigid body physics to split on an exact point on an exact frame?

I have a chain around a character and in the center of the chain there is a "padlock" type device, I want it to open and let the chain fall mid animation. Can this be achieved in Blender with rigid body physics or does everything have to be animated by hand?
Yes - you can animate the properties of the rigid body constraints to effectively disable the link.

For example, here is a chain of cubes, linked together with a series of Rigid Body Constraints - each set to a Stiffness of 40. At a certain frame the keyframes Stiffness drops to zero, splitting the 'chain' :



The produces the following when animated :