The presence of skin cells at a crime scene

Should the presence of skin cells at a crime scene or on a victim’s body be a sufficient basis for DNA evidence alone to lead to a criminal conviction? What if someone has a skin condition involving shedding skin cells, such as psoriasis, and a crime victim picked up those cells unknowingly from riding in a taxicab were those skin cells were left behind by the previous passenger? If you were a prosecutor, what specific things would you communicate to the police about their crime scene investigations? What specific things would you communicate to jurors about DNA evidence?