DNA expert witnesses dueled last week in the New York murder trial of Timothy Matthew Jacoby, accused of shooting and killing 55-year-old Monica Schmeyer during a 2010 burglary. Prosecutors are seeking the death penalty for the murder, so the testimony of DNA experts will prove crucial to the defendant’s fate.
Firearms Expert Testifies in Murder Trial
Earlier in the murder trial of Timothy Jacoby, prosecutors called state police Cpl. David Krumbine to link the bullet that killed Monica Schmeyer to shell casings found on a farm owned by the defendant. According to the prosecutors, Jacoby killed Schmeyer during a burglary attempt in her secluded home. In addition to connecting the shell casings at Jacoby’s farm to the bullet that killed Schmeyer, Krumbine was asked to analyze the pistol barrel found in a Mason jar filled with coins in Jacoby’s home to determine if the bullet matched.
Krumbine’s expert testimony informed the jury that the barrel found in Jacoby’s home was the same caliber as the bullet that killed Schmeyer. Going further, Krumbine pointed out a defect in the barrel – a gouge at its mouth that would influence bullets fired from the gun. The bullets Krumbine test-fired from the gun had gouges as a result of the barrel, as did the bullet that killed Monica Schmeyer. However, during cross-examination Cpl. Krumbine admitted that there were several other scratches in the barrel that made it impossible to determine for certain if the fatal bullet was fired from it.
Although Krumbine testified that the shell casings found on Jacoby’s farm and the bullet that killed Schmeyere were fired from the same gun, defense attorneys found enough room to raise doubt that Jacoby had committed the murder. To create further questions, Jacoby’s lawyers called a DNA expert witness to separate him from the scene.
Defense Calls DNA Expert Witness
Jacoby’s defense team called Katherine Cross, the DNA technical leader at Guardian Forensic Services, as a DNA expert witness to call into question evidence found under Schmeyer’s fingernails. Earlier in the trial, prosecutors connected the DNA found in the fingernails to Jacoby, but Cross told jurors that did not necessarily place the defendant at the scene.
According to Cross, the police investigators conducted too limited a test when analyzing the DNA evidence found at the murder scene. Cross’s expert DNA testimony explained to jurors that there are several genetic markers that are used to connect the evidence to a suspect, and police used too few to come to a solid conclusion. The police used 11 markers to identify Jacoby, but in Cross’s expert opinion, the tests were not thorough enough. Telling jurors, “More markers could define whether it’s Jacoby [or someone else],” Cross testified that she would have examined 23 markers.
Cross concluded her expert DNA testimony by saying that the police’s investigation left the possibility that up to 127 other individuals in the area who could have the same 11 markers as Jacoby, meaning the evidence was insufficient to identify the defendant.
Prosecutors Look to DNA Expert Witness in Murder Trial
To counter Mrs. Cross, prosecutors called a DNA expert witness of their own who cast doubt on the defense team’s expert conclusions. Christian Westring, director of criminalistics at NMS Labs, criticized Cross’s calculations and, accordingly, her conclusions. Saying that Cross’s math was misleading because there are not 127 people in the area who could have the same 11 markers as Jacoby, Mr. Westring attempted to rebut the attack on the prosecution’s DNA evidence.
Westring said that in his expert opinion, Cross’s testimony was “irrelevant,” and that he didn’t “see the value in the calculation [because] the mathematics are incorrect and the philosophy behind [the] numbers are flawed.” Finding Cross’s DNA expert testimony to be misleading, Westring acknowledged that more thorough testing was possible, but emphasized that the investigation was sufficient to narrow the DNA found to Jacoby. As DNA becomes a regular part of criminal trials, the Jacoby murder case serves as a relevant example of how prosecutors and defense attorneys rely on DNA expert witnesses to argue over the quality of the tests and the validity of their conclusions.