DNA Limitations
Defense argument against bind-over
IV. The DNA Cannot Establish Who Used the Rifle or When
The State uses enormous statistical numbers to make the DNA evidence sound dispositive. But the State’s own expert explained the limitations. She testified that DNA can appear on an object for numerous reasons and that the laboratory does not offer an opinion about what activity produced it. She could not determine when the DNA was deposited. DNA can remain recoverable for years or decades under favorable conditions. Source: rev.com
- that he possessed it on September 10;
- that he transported it to UVU;
- that he carried it onto the roof;
- that he loaded the relevant cartridges;
- that he fired it;
- or that he was the last person to handle it.
The DNA proves biological material was present. It does not reconstruct conduct.
The State’s case becomes even less clean when the Court considers the mixtures and other contributors. The evidence established that Twiggs’s DNA was present on crucial associated material. One tested sample was interpreted as a mixture involving Twiggs and Mr. Robinson. The defense elicited that investigators had directed the examiner to treat Twiggs as an expected or elimination contributor because he lived with Mr. Robinson. Source: rev.com
The towel was not collected from their shared home. It was recovered outside, near UVU. The examiner acknowledged that it was not found in a location where Twiggs’s DNA would naturally be expected merely because he was a roommate. Investigators nevertheless told her that they suspected the towel had originated in the residence and that Twiggs should be treated as an expected contributor. Source: rev.com That does not prove Twiggs committed anything. It does prove the DNA cannot be presented as a simple, one-person trail leading exclusively to Mr. Robinson.
“Mr. Robinson’s DNA means he used the object” — then argue “Twiggs’s DNA means nothing because he lived in the home.” Both profiles require the same scientific caution. If shared-home transfer or prior household contact explains Twiggs’s DNA, it can also explain Mr. Robinson’s. If DNA proves active use, the State must explain Twiggs’s presence. It cannot have the science both ways.