> Why would DNA testing have anything to do with fingerprints?

Just the Guardian being the Guardian. Fortunately, they link to their source which states "three DNA experts examined testing from the knife 'and each has independently concluded that Mr. Williams is excluded as the source of the male DNA on the handle of the murder weapon'" [1].

[1] https://apnews.com/article/missouri-death-row-inmate-dna-evi...

Thanks for that. Wow, that's some shoddy journalism: does the Guardian writer not know the difference between DNA and fingerprints?

Apparently "staff with the prosecutors’ office had mishandled the weapon after the killing – touching it without gloves before the trial," which "made it impossible to determine if Williams’s fingerprints could have been on the knife earlier." Looks like wires getting crossed and nobody editing.

(Of course, that comes from the same Guardian article.)

Maybe a clumsy attempt at referring to DNA fingerprinting [0]?

[0] https://en.m.wikipedia.org/wiki/DNA_profiling