A week later, Linda Byrne was shown a second line-up, and was again unable to recognize her attacker.

The evidence found during the medical examination of Linda Byrne was submitted to a forensic laboratory for analysis, along with samples of Steven Murphy's own DNA, blood, hair fibers, and fingerprints. At trial, an expert criminalist (Daniel Quinn) testified that the blood type sample from Steven Murphy matched the blood evidence found on Linda Byrne, and was conclusive beyond a reasonable standard of scientific certainty.

The results of the other types of evidence (DNA, hair fibers, and fingerprints) were inconclusive about the defendant’s guilt.



Question 2 (C)
At this point, what would you estimate to be the probability that Steven Murphy sexually assaulted Linda Byrne? Please choose a number between 0% and 100%, where 0% means, "absolutely sure he did not do it" and 100% means, absolutely sure he did do it": _________%



During the cross-examination of the expert witness the defense asked about the error rate for the laboratory that analyzed the blood evidence. The expert witness who presented that evidence indicated that errors occur in approximately 2 cases out of every 100 tests the lab conducts.

However, during the week that the evidence samples for this case were tested, a new laboratory procedure was used and incorrectly applied for blood analysis. As a result, the laboratory made errors in 5 of the 10 cases examined that week. Unfortunately, the sample taken from Linda Byrne was small, and used up in the initial tests. Thus, subsequent tests to confirm the identification could not be performed.

In addition, the defense asked questions about how the evidence samples were collected, preserved, and brought to the lab. The expert witness indicated that although the sample was collected and preserved following appropriate procedures, the chain of custody was not correctly followed when the sample was transported to the lab. Instead, the person who transported the evidence from the police department brought the samples home overnight before taking them to the laboratory.
A week later, Linda Byrne was shown a second line-up, and was again unable to recognize her attacker.

The evidence found during the medical examination of Linda Byrne was submitted to a forensic laboratory for analysis, along with samples of Steven Murphy's own DNA, blood, hair fibers, and fingerprints. At trial, an expert criminalist (Daniel Quinn) testified that the hair fiber sample from Steven Murphy matched the hair fiber evidence found on Linda Byrne, and was conclusive beyond a reasonable standard of scientific certainty.

The results of the other types of evidence (DNA, blood, and fingerprints) were inconclusive about the defendant’s guilt.



Question 2 (D)
At this point, what would you estimate to be the probability that Steven Murphy sexually assaulted Linda Byrne? Please choose a number between 0% and 100%, where 0% means, "absolutely sure he did not do it" and 100% means, absolutely sure he did do it": _________%



During the cross-examination of the expert witness the defense asked about the error rate for the laboratory that analyzed the hair fiber evidence. The expert witness who presented that evidence indicated that errors occur in approximately 2 cases out of every 100 tests the lab conducts.

However, during the week that the evidence samples for this case were tested, a new laboratory procedure was used and incorrectly applied for hair fiber analysis. As a result, the laboratory made errors in 5 of the 10 cases examined that week. Unfortunately, the sample taken from Linda Byrne was small, and used up in the initial tests. Thus, subsequent tests to confirm the identification could not be performed.

In addition, the defense asked questions about how the evidence samples were collected, preserved, and brought to the lab. The expert witness indicated that although the sample was collected and preserved following appropriate procedures, the chain of custody was not correctly followed when the sample was transported to the lab. Instead, the person who transported the evidence from the police station brought the samples home overnight before taking them to the laboratory.