circumstantial evidence

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Evidence not bearing directly on the fact in dispute but instead on an attendant circumstance, such as the defendant's blood type or shoe size, from which the judge or jury might infer the occurrence of the fact in dispute.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun evidence providing only a basis for inference about the fact in dispute