Court Filing
EXHIBIT S-3 Amended Supplemental Expert Disclosure: Taylor Maichak The State hereby discloses Taylor Maichak, Forensic Scientist III, as an expert witness in the field of forensic DNA, which includes, but in no way is limited to, DNA extraction, quantification, amplification, analysis and interpretation / analysis (including but not limited to STR data, Y-STR data; and STRmix probabilistic genotyping). The State hereby incorporates its previous response and attachments filed on December 18, 2024 and is hereby supplementing its response as follows. Taylor Maichak is currently employed as a Forensic Scientist III with the Idaho State Police Forensic Service, specifically in forensic DNA. Her CV with further qualifications is attached. Particularly, Maichak can be expected to testify as to the testing of several lab items. She will discuss the process of DNA analysis by utilizing the Polymerase Chain Reaction (PCR), which was used in this case to generate a Short Tandem Repeat (STR) profile. Additionally, Maichak may discuss lab testing protocols, procedures, and the consumption of evidence. Consumption of evidence is using an entire sample for DNA testing. This is typically utilized when a low-level of DNA is anticipated. Maichak previously testified in this case during grand jury proceedings and can be expected to testify in the same manner. More specifically, Maichak will provide an explanation of what DNA is, how DNA can be collected, and how DNA can be used. Deoxyribonucleic acid (DNA) is genetic material contained in cells that may be utilized for human identification. DNA may be present on an item in the form of biological materials such as blood, semen, and saliva or may be left on an item when it is handled. Biological evidence and possible / potential DNA EXHIBIT S-3 STATE'S EXHIBIT exhibitsticker.com Amended Supplemental Expert Disclosure: Taylor Maichak (Sealed) 1 S-3 CR01-24-31665 evidence is collected for preservation and may be sent for further testing by qualified analysts. DNA can be collected by swabbing an item or by taking a cutting directly from an item. Reference DNA samples can be collected directly from individuals. DNA can be used to identify individuals, link individuals to crime scenes, link crime scenes, as well as exclude individuals from DNA profiles that we obtain. Maichak will explain the four steps of DNA analysis such as the 1) extraction of DNA from cells, 2) the quantification of DNA (how much DNA is present in a sample), 3) the amplification of DNA (generating copies of DNA), and 4) the generation of a DNA profile for comparison. Maichak will explain how DNA STR profiles are developed. 1. Extraction: add chemicals to break open all the cells to release the DNA. 2. Quantification: amount of DNA is measured within each sample. 3. Amplification: copy the specific locations of DNA using polymerase chain reaction. 4. Developing a DNA profile: visualize the DNA profile, which looks like peaks on a graph. Once we have our DNA profiles we can begin interpreting the data and making comparisons. As applicable, profiles may then be entered into the Combined DNA Index System (CODIS). CODIS is a national collection of DNA profiles maintained by the FBI. It contains convicted offender profiles as well as profiles obtained from evidence, and can be used to identify a suspect, generate potential leads, or link crime scenes together. Upon entry, profiles are automatically searched against the database and generate “ hits ” when a match occurs. In Idaho, individuals convicted of felonies and those placed on the sex offender registry must be entered into CODIS. Idaho also allows for the entry of unidentified profiles generated from evidence associated with a crime, when that profile is believed to be from the putative perpetrator. Idaho also allows for the entry of DNA EXHIBIT S-3 Amended Supplemental Expert Disclosure: Taylor Maichak (Sealed) 2 profiles associated with unidentified human remains or living people unable to identify themselves. The profiles are entered by the reporting analyst and reviewed during technical review. Each state also has one CODIS Administrator who is responsible for ensuring only approved profiles are entered. Maichak will discuss at length the generation of a DNA STR profile from item 1.1 (swab of front strap of knife sheath), which Maichak concluded to be from an unknown male (ultimately deemed “ male A ”). There are STR locations specific to the Y chromosome, which only males have. When a peak is present at these locations it indicates that one or more donors are male. This conclusion can be found in report 4. Maichak may also discuss her interpretations and conclusions regarding the mixture of DNA obtained from items 1.2 (swab of edges on handle portion of knife sheath), 1.3 (swab of edges on blade portion of knife sheath), and 1.4 (swabs of stains on back of knife sheath). Maichak will discuss how individuals or reference samples are excluded as contributors to a DNA mixture or source. Comparisons can be between evidence and reference samples to include or exclude an individual from a single source or mixture DNA profile. For exclusions to single source profiles, the exclusion can be made by visually comparing DNA profiles. For mixture samples, a software tool (STRmix) can be used to aid in this comparison. Maichak will also discuss the partial DNA profile obtained from item 1.2, which indicates a mixture of three individuals, at least one of which is male. However, due to low level results, no comparison could be made. Low level results are results with limited data that are not suitable for comparison. Determining if a sample is suitable for comparison is EXHIBIT S-3 Amended Supplemental Expert Disclosure: Taylor Maichak (Sealed) 3 guided by ISPFS policies but analyst discretion may also be considered when appropriate. Per the ISPFS Biology / DNA Casework Analytical Methods, results that contain minimal data (typically results at fewer than 6 loci) should not be interpreted. Additionally, the interpretation of DNA results should take into account the DNA results obtained, the nature of the sample, the condition of the profile, any forensically valid assumptions made, and should be scientifically justifiable and based on the collected experience and knowledge of the laboratory and the scientific community. The guidelines outlined in the Analytical Methods are designed to provide a general foundation for interpretation but may not account for all scenarios that will be encountered. In those scenarios the forensic scientist and DNA technical lead will determine the course of action that is scientifically most appropriate. Maichak may explain the partial DNA profile obtained from item 1.3, which indicates a mixture of DNA from at least two individuals, at least one of which is male. However, due to low level results, no comparison could be made. Maichak may explain the mixture of DNA obtained from item 1.4. Additionally, Maichak will explain how a DNA STR profile was generated from item 87.1 (cutting from one Q-tip style swab from 127 Parkside Ave, Blakeslee, PA (Pennsylvania State Police Department) which was taken from trash from the Kohberger residence, at 119 Lamsden Dr., Albrightsville, PA). Maichak determined the DNA profile obtained from item 87.1 was from an unknown male (ultimately deemed “ male E "). Maichak concluded Male E was not the source of DNA previously obtained from item 1.1. However, Maichak was able to conclude that from the DNA profile obtained from item 87.1 (male E) and that obtained from item 1.1 (male A), male E cannot be excluded as EXHIBIT S-3 Amended Supplemental Expert Disclosure: Taylor Maichak (Sealed) 4 being the biological father of male A. Maichak made this conclusion using the single parentage index. The single parentage index for the loci examined was 19,070,000. Maichak will discuss that at least 99.9998% of the male population would be expected to be excluded from the possibility of being the biological father of male A. This conclusion can be found in report 17. The single parentage index is a statistical value that compares two probabilities: the probability of seeing the child's genetic information if a tested individual is the biological parent of the child versus if a random individual (either man or woman) from the population is the parent. This calculation only uses one parent for comparison. Half of your DNA is obtained from your mother and half from your father. " Single parentage index for the loci ” means that we are only discussing the loci tested in this case. Further, Maichak compared several items in this case, including more items listed in Report 17 (Bates Pages 5732-5758). Maichak may discuss the partial profile obtained from 93.1 (swab of Dunkin cup lid from 127 Parkside Ave, Blakeslee, PA) being consistent with male E's profile. Maichak may also explain the low levels of male DNA (or no presence of male DNA) on other items in Report 17. EXHIBIT S-3 Amended Supplemental Expert Disclosure: Taylor Maichak (Sealed) 5