Which of the following is true about circumstantial evidence?

Circumstantial evidence refers to evidence that suggests a fact or event without providing direct proof. It often relies on inference, which means that to establish a conclusion based on this type of evidence, one typically needs additional evidence to strengthen the case. In legal contexts, while circumstantial evidence can be compelling, it usually does not stand alone to prove guilt beyond a reasonable doubt without supplementary support, such as corroborating evidence or witness testimony.

This makes the first statement accurate, as it highlights the often necessary role of additional evidence in supporting what circumstantial evidence suggests. The other options do not align with the nature of circumstantial evidence: it is not direct evidence of a crime, it is not the only form of evidence allowed in court, and while witness testimony may not always be necessary, circumstantial evidence is often used in conjunction with it to present a stronger case.