Yes, DNA evidence is circumstantial since we can make inferences about the sheath. I think the example used early on is that the sheath could have been stolen from BK by the perp.
So other evidence is needed to prove that only BK could have been responsible for the murders.
I thought DNA evidence was more direct than circumstantial. If DNA isn't direct evidence then what about fingerprints?
Obviously I need to do more research. I know for sure if a person/witness actually sees a killer commit murder, then gives testimony about it, their testimony is considered direct evidence.
I like the way you bring up the point that we can make inferences about the DNA found on the sheath. You mention the sheath could have been stolen from BK. Someone else mentioned BK touching the sheath in the store but he didn't buy it. Someone else mentioned BK being set up by someone, that someone planted his sheath at the crime scene.
When I look at it like this I can understand better why DNA might be considered circumstantial.
On every murder thread there are discussions that strongly discount the circumstantial evidence, saying it doesn't prove anything. However, from what I have seen, when you pair circumstantial evidence with DNA evidence you get a conviction almost every time. Even though DNA is apparently circumstantial evidence, nonetheless, it is considered very strong evidence by itself. When you take DNA evidence and add alot of circumstantial evidence with it, the DNA evidence becomes that much stronger.
I agree with posters who think the circumstantial evidence (we know of) might not meet the threshold for the required "beyond a reasonable doubt" to get a conviction in this Case.
But if expert witnesses can convince the jury that the sheath DNA is BK's DNA, and then the jury sees all the circumstantial evidence on top of that, I think there will be enough "beyond a reasonable doubt" evidence for a conviction.
Just my opinion and like I said, I need to do more research:
Circumstantial Evidence vs Direct Evidence.