1) Street light burns out but hasn't been replaced yet, making street dim
2) Dim lighting leads bystander to mistakenly conclude that accused was present at scene of crime
...
5) Thus, for the want of a light bulb, someone is put to death.
My contention is that it is a failing of the process for the Jury to reach the conclusion based on a forensic analyst's mistake. I'm not an expert on courtroom proceedings, but I certainly hope that if I am ever asked to give expert testimony in court, I will not look the jury in the eye and claim in loud, ringing tones that I am 100% confident of my findings when spelunking through a database format I didn't write that was written by code I haven't examined line by line.
If I was foolish enough to make claims like this, I hope someone would cross-examine me properly. I hope that someone, somewhere would suggest that there might be any number of reasons why the word "chloroform" might appear on the hard disk in that spot and give alternate explanations. And so on, and so forth.
If people are being sent to Death Row based on what looks to me like incredibly scanty evidence, I don't think the scanty evidence is the problem, I think the process for evaluating evidence is the problem.