I'm finishing my basement. It's approximately 1500 square feet. I will be dividing the basement into 2 bedrooms an office and a large open area. I only have one cold air return. It is by the ceiling near the furnace. This cold air return will end up in one of the bedrooms. Do I need additional cold air returns?

If you expect comfort in those rooms when the doors are closed, yes, you do. They also need to be sized so that balance is maintained in the system. Too big and they will remove conditioned air from the rooms...too small and the air velocity at their grilles may be too high and therefore too noisy. The ducts leading to them must be similarlt sized to maintain balance. It's probably a job for a professional to size and install the ducts and grilles.

Where is the furnace located? Basement,first floor, attic?

My first response to this is no. Main returns should be located on living levels such as 1st 2nd floors. If the origional return has been located in the basement the design was wrong and needs to be evaluated by a professional heating contractor.

Ideally having independent returns in rooms is ideal. Not having them can cause the room to pressurize when the door is closed and cause the room air flow to become poor.

But we need to know where exactly is the main return, is it only located within the basement or is there other returns on each level of the house.

Also on another note. These bedrooms your building, have you installed a 2nd form of egress to them? Basement bedrooms are often times unsafe if there is a fire in the house. In our area they require either a large window in which a fireperson with gear can enter safely or multi doors where someone trapped can leave the basement by another route.