Rebus knew what they'd be looking for - murder weapon to start with, and then trace evidence such as blood.

Drain - Used to remove excess fluids, such as blood.

Doppler looks at how sound waves reflect off moving objects, such as blood.

"The human knee does make a very unique shape, especially when you have a malleable background such as blood."

Patent prints can be left on a surface by materials such as ink, dirt, or blood.

Over half of the grandparents had stress-related illnesses, such as high blood pressure and depression.

This action does not work for some stains, such as blood.

No trace of biological material such as blood, skin or hair were found on the tools.

The test may also be done using other types of samples, such as spinal fluid, blood, urine, or tears.

There was no physical evidence, such as bruises or blood, linking Smith to the crime.