We've had cases over the years where we get the offender's fingerprint in the victim's blood. Evidence doesn't get any stronger than that. We've got people in jail for murder with nothing more than a fingerprint. Fazekas said that the quality and presence of fingerprints depend on several factors ranging from the weather to the way a person perspires. Some people sweat more than others.
Sweat is a part of it.
When you touch your hair or your nose, you're transferring grease and oil to your fingers. He added that it also depends on the surface that was touched. Fingerprints, of course, can be easily lifted from glass, metal, wood, leather and vinyl. But it is almost impossible to get prints from rugs and fabrics. I've been surprised a few times.