## Population Genetics:

- The probability of a Caucasian American having a 16, 17 combination for D3S1358 is (0.200 X 0.281) 0.0562.

- The probability of an African American having a 16, 17 combination for D3S1358 is (0.248 X 0.242) 0.060.

- The probability of a Caucasian American having a 16, 17 combination for D3S1358, and a 5, 9 combination for TH01 is (0.0562 X 0.002 X 0.114 002 X 0.114) 0.0000128.

- The probability of a Caucasian American having a 16, 17 combination for D3S1358, a 5, 9 combination for TH01 and an 11, 14 combination for D18S51 is (0.0000128 X 0.017 X 0.137) 0.0000000298.

- Forensic analysis uses many CODIS markers as opposed to just one or two because as you start adding additional markers, the probability for that particular combination of STR’s within the population decreases. The above calculations support this claim. In a above, only to markers were analyzed. The probability of this combination appearing in the population was 0.0562. With the addition of two more markers, as in c above, made the probability decrease from 0.0562 to 0.0000128. A final addition of two more markers decreased the probability of the combination from 0.0000128 to 0.0000000298.

- The finding of blood with an STR combination of 16, 17 for D3S1358, a 5, 9 for TH01 and an 11, 14 for D18S51, does call the eyewitnesses claim into question. The eyewitness claimed that it was a Hispanic man who stole her car. It would however not be possible for a Hispanic man to have this specific combination of STR’s. This is because when you look at the frequency chart above, the frequency for an STR length of five on the TH01 STR for Hispanics within the population is zero. Therefore, there is zero probability that this combination would appear in a Hispanic person.

- The probability of an African American having a 16, 17 combination for D3S1358 is (0.248 X 0.242) 0.060.

- The probability of a Caucasian American having a 16, 17 combination for D3S1358, and a 5, 9 combination for TH01 is (0.0562 X 0.002 X 0.114 002 X 0.114) 0.0000128.

- The probability of a Caucasian American having a 16, 17 combination for D3S1358, a 5, 9 combination for TH01 and an 11, 14 combination for D18S51 is (0.0000128 X 0.017 X 0.137) 0.0000000298.

- Forensic analysis uses many CODIS markers as opposed to just one or two because as you start adding additional markers, the probability for that particular combination of STR’s within the population decreases. The above calculations support this claim. In a above, only to markers were analyzed. The probability of this combination appearing in the population was 0.0562. With the addition of two more markers, as in c above, made the probability decrease from 0.0562 to 0.0000128. A final addition of two more markers decreased the probability of the combination from 0.0000128 to 0.0000000298.

- A female eyewitness has identified a Hispanic male as a having stolen her car. The eyewitness noted that the man who stole her car was bleeding profusely from a head wound. Her car was recovered and male blood with a 16, 17 combination for D3S1358, a 5, 9 combination for TH01 and an 11, 14 combination for D18S51 was found on the driver’s seat and steering wheel. Does this finding call the eyewitness evidence into question? Explain your answer.

- The finding of blood with an STR combination of 16, 17 for D3S1358, a 5, 9 for TH01 and an 11, 14 for D18S51, does call the eyewitnesses claim into question. The eyewitness claimed that it was a Hispanic man who stole her car. It would however not be possible for a Hispanic man to have this specific combination of STR’s. This is because when you look at the frequency chart above, the frequency for an STR length of five on the TH01 STR for Hispanics within the population is zero. Therefore, there is zero probability that this combination would appear in a Hispanic person.