In Deuteronomy 17:6 and II Corinthians13:1, the passages refer to the "two or three witnesses." I assume these are eyewitnesses. Does DNA count as an eye witness for justice biblically? So when individuals are convicted on DNA evidence alone for their crimes and incarcerated or put to death, is that biblical or not?
Under the Old Testament law, a witness was any independent source of information that could confirm or deny a fact. Most of the time we are referring to a person's testimony, but it can be other evidence as well. For example, in a trial concerning the misrepresentation that a woman was a virgin before marriage, the presentation of a cloth showing blood from when the hymen was broken constituted a witness (Deuteronomy 22:17). When Jacob and Labon made a covenant, a pillar of stone was raised to serve as a witness that the covenant was made (Genesis 31:48).
Implied in all of this is that the witnesses must agree to the fact to be established. Contradictory witnesses were handled differently.
One important aspect of witnesses is that no person could be put to death on the testimony of only one witness. "Whoever kills a person, the murderer shall be put to death on the testimony of witnesses; but one witness is not sufficient testimony against a person for the death penalty" (Numbers 35:30). "Whoever is deserving of death shall be put to death on the testimony of two or three witnesses; he shall not be put to death on the testimony of one witness" (Deuteronomy 17:6).
Thus, under the Mosaical law, a person could be punished based on a single witness, but he could not be put to death. If we were living under a similar set of laws, DNA would count as one witness, but it wouldn't be enough by itself to trigger a death penalty. After all, all it says is that material containing the DNA was found at the scene of the crime. It doesn't testify as to how it came to the crime scene.
Let's take the case of rape. A woman's testimony would be insufficient by itself to gain a death penalty. But add the statement of someone walking by who heard her scream or saw the man leave or in modern-days DNA left behind, then the multiple witnesses would allow a death penalty to be invoked.