Making a Murderer. Show says Innocent. Skeptics say...

Also luminol had been used to detect it.

Funny, that's not what John Ertl (WI State Crime Lab) testified to.

Ertl testified that the luminol reaction was not consistent with what one would expect from bleach, and that they were unable to determine what it was.

Relevant excerpts from Ertl's testimony are below, with emphasis added for convenience, from: jury trial transcript for day 6.

From direct-examination of Ertl, starting on page 60:

Q. Can you describe this smear in greater detail.

A. Roughly 3 to 4 foot diameter area. Faintly glowing under the luminol. No specific spots or stains. Couldn't see anything with the lights on. Just swabbed several places where the luminol had been reacting, tested with phenolphthalein and did not get a reaction with the phenolphthalein.

Q. All right. So this is that large area you were talking about?

A. Yes.

Q. So what did that tell you, as a forensic scientist, about that large area and its reaction to luminol but did not react to the more specific phenolphthalein test?

A. Well, there was something that had been spread out in a large area that was reacting. I don't know what. And what cross reacts, cleaning chemicals dilute blood, would react, but it may not show up with phenolphthalein if it was diluted enough. So there was really nothing for us to collect from there.

From cross-examination of Ertl, starting on page 120:

Q. Luminol is this substance that reacts to a number of different things besides just blood, right?

A. That's correct.

Q. Other kinds of chemicals, you mentioned cleaning agents, bleach reacts real highly to that, very strong?

A. Yes.

Q. Which means very bright?

A. Bright and fast, yes.

[snip]

Q. And this is a garage -- Let's go to the garage floor for a minute, where you said you had a faint reaction in this little area, 3 X 4 area.

A. Right.

Q. Not a real bright, quick reaction like you get with bleach, for instance?

A. Right.

/r/skeptic Thread Parent