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Malcolm Mac Kinnon

Using Helianthus annuus Seeds to Solve A Mystery Name: Supreet Babbar Student Number: 999739074 Practical Section: 12 Teaching Assistant: Chris Kong-Kee Submission Date: November 19th, 2012 1 Page Introduction: Forensic botany is the use of botanical evidence in criminal investigation. The recognition, collection and preservation of plant materials can play a vital role in determining the manner or time of death. It can also be used to investigate if the death was accidental, a suicide or a homicide (Coyle et al, 2005). This concept of forensic botany can be applied to the case of Roger T. Peterson‟s suspicious death. The victim‟s body was found under a tree behind his store. In addition to the evidence for the blunt force trauma to the body, Helianthus annuus seeds were found on and around the body (Rush et al. 2012). These seeds were compared to the seeds collected from the home the prime lead suspect. In order to prove that the suspect was at the scene of crime, it was necessary to answer the question if the two seed samples collected as evidence were similar. Confirmation or the rejection of the two seed samples being similar is not enough to prove that the suspect is guilty or innocent. In this investigation environmental factors such as temperature and moisture were not taken into account, although they have shown to affect the physical characteristics of Helianthus annuus. Based on other circumstantial evidence collected including fingerprints of Bobby Walden found at the cash and on the back door, along with his habit of leaving a trail of Helianthus annuus seeds and his history of petty thefts it is hypothesized that he was at the scene of the crime and the prime suspect of this case. In addition statistical analysis of the seed samples was also conducted. The hypothesis is test by comparing the calculated sample t test value to the critical value. If the sample t statistic was greater than the critical value, this data demonstrates that the two seed samples from the victim and suspect are different, rejecting the null hypothesis. The hypothesis is test by comparing the calculated sample t test value to the critical value. If the sample t statistic was lower than the critical value, then this data demonstrates that the two seed samples from the victim and suspect are the same, failing to reject the null hypothesis. Abstract: The purpose of the experiment was to analyze the seed evidence collected from the victim and the suspect to help solve the murder case of Roger T. Peterson. It was hypothesized that Bobby Walden, the prime suspect, had a role to play in the death of the victim and had been at the scene of the crime. The circumstantial evidence targeting Bobby Walden, were his fingerprints found in the store and the trail of his favourite snack, Helianthus annuus seeds. A total of thirty five seeds each were collected from Bobby Waldon‟s house and from on and around 2 the victim‟s body. The length (in mm), width (in mm), depth (in mm), weight (in grams) and volume (in mm ) of Page all seeds were recorded and transferred to an Excel spreadsheet. The mean, standard error value, standard deviance, and variation values were generated through the calculations based on the measured characteristics. In addition, the sample t statistic values were calculated for the measured characteristic of the seeds collected from the suspect and the victim. The t statistic values were found to be higher than the t critical value (more than 1.995). This confirms the rejection of the null hypothesis, indicating that the seed sample characteristics of those of the victim and suspects were different. Furthermore, it would be unfair to implicate the suspect as having been at the scene of crime when the victim died, as his seeds did not match up to seeds found at the crime scene. Method On the morning of August 15, 2012, at Highland Creek, Roger T. Peterson was found murdered in his pet store. Helianthus annuus seeds were collected from around the body of the victim and from the house of the prime suspect, Bobby Walden. The seeds were sent to the Forensic Botany Department at UTSC to help with the investigation of this mysterious death. A total of thirty-five seeds each were collected and analyzed from the suspect and of those found near the victim. The botanists were divided into two groups and were provided randomly with packets of Helianthus annuus seeds. The packet contained six to seven Helianthus annuus seeds. A marker was used to number the seeds in the packets provided to the forensic botanist to analyze. The botanist used a ruler to measure the length (in mm), width (in mm) and depth (in mm) of the seeds. The volume was calculated by using the following formula, V = 4π/3 (length/2)(width/2)(depth/2). The mass of each seed was measured by using a top-loading balance (in grams). All the measurements were recorded on the “Data Sheet” (Rush et al. 2012). The data of the seeds where transferred to an Excel spreadsheet and the descriptive statistics were calculated (mean, maximum, minimum, standard deviation, variance etc.). A t-test (Mean – 1ean |/√ 2SEM 12 + SEM ) was constructed to compare the measurement variables (length, width, volume, depth and weight) of the 2 Helianthus annuus seeds taken from the suspect to those collected from the victim. The t statistic values were compared to the critical values, in order to determine if Mr. Walden was present at the scene of crime where the body was found and could be a potential lead suspect in the case. Results: 3 Page The characteristic of length, width and depth of Helianthus annuus seeds from the suspect and the victim were compared and analyzed and. The measured characteristics were compared against the descriptive statistics, which included the mean, standard deviation, minimum and maximum values of both samples (Refer to Table 1). From this constructed table, the values obtained for length, width and depth of the seeds were shown to have perceptible different between the victim and suspects seeds. The mean value for length, width and depth were notably higher for seeds collected from the suspect in comparison to the seeds found on and around the victim. The maximum and minimum measurement values of the data set for length, width and depth are consistently higher in the seeds of the suspect than of the victim. In addition, the values for standard in terms of length, width and depth were larger for the seeds of the suspects in relation to those of the victim. 4 Page Table 1: Measurement Characteristics of Helianthus annuus Seeds collected from the Victim and the Suspect Length (mm) Width (mm) Depth (mm) Victim Suspect Victim Suspect Victim Suspect Minimum 10 11 5 4 2 2 Maximum 18 20 9 10 5 8 Mean 12.
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