2 Person Mixture #1

1. 2 Person Mixture #1 Jeans of Suspect

2. Scenario • Victim and Suspect were the only ones home • Suspect says Victim was playing with a hand gun • Gun went off, Victim is shot • Suspect said “I should have stopped him” • Suspect said he tried to render aid, which explains the blood on Suspect’s jeans

3. The Egram

4. The Data Table

5. Our lab would • We don’t interpret mixtures • Include/exclude but don’t have a stat for this • Include both and do stat • Include only suspect and do stat • Include only victim and do stat

6. IF you do a stat, your lab does • CPI • LR • 2 person RMP of some sort • Assume suspect on own jeans and do RMP on foreign • Deconvolute and (try) to give SS stat 30 0 of 30 Countdown

7. Match to Suspect • All alleles of Suspect found on his own jeans • Orange highlight means an exact match • Yellow means included in the mixed profile

8. Match to Victim • All alleles of Victim found on suspect jeans • (Suspect said they would be there)

9. The mixture interpretation window

10. The mixture interpretation window This window is where you interact with your data. Some parts of this window are static, some areas “change” the data, but the original data table is always left untouched.

11. The mixture interpretation window This area is where the raw data is presented. The Alleles, RFUs and BPs never change here. You can navigate from locus to locus, either by kit order or from most alleles to least alleles.

12. The mixture interpretation window This area is where you can choose a different sample, set for the number of contributors, define references, and get quickly to the final stat. Eventually it will bring you straight to the egram.

13. Defining a reference When you click the “References” button, a window opens where you can use a drop down menu to select up to 6 references from any sample in any table you may have open.

14. Defining a reference This is a close up of the Reference window. If a reference is applied, the underlying table will show it.

15. The mixture interpretation window This area is where you can track the proportions of the user defined interpreted profiles as a result of the deconvolution process.

16. The mixture interpretation window This area is where you can adjust your interpretation parameters. Peak height ratios, minimum peak height, minimum proportion, and homozygote (stochastic) thresholds are all adjustable. You can also ignore low level alleles and “lock” a locus you’ve finished.

17. The mixture interpretation window These buttons are used to start a deconvolution or interpretation process.

18. The mixture interpretation window This area is for some “what if” scenarios. You can correct for stutter, label a user defined deconvoluted profile, or ignore an allele. If you do correct for stutter, the values are highlighted.

19. The mixture interpretation window This shows that we’ve corrected for 100% of possible stutter and the RFUs for alleles 12 and 13 have been recalculated by subtracting 8% of the peak to the right.

20. The mixture interpretation window This shows us the conditions we’ve set for this locus. The “viable” contributor combinations below depend on these conditions. You can also change the font size to help see everything.

21. The mixture interpretation window This tells us that we’ve got a 2 person mixture and there are 4 alleles here. The “category” is listed and although there are 3 combinations possible, only 1 combination meets the criteria we’ve set.

22. The mixture interpretation window If we turn off the reference and lower the PHr to 30%, all 3 combinations are now displayed.

23. Now back to the mixture

24. Setting it up for what we know In the Reference window we can tell it to “Auto-call references” and also to list the foreign alleles.

25. Setting it up for what we know Click the “View call report” button and a new window will open that you can use to interpret or deconvolute the sample.

26. Setting it up for what we know Because we told it to “Auto-call references” the new table has the known contributor on the top line, and if there is only one option for the remaining type, that is on the second line. The proportions are graphed for each contributor where a proportion can be determined.

27. Setting it up for what we know I’ve used the re-name function to define what I want to call the profiles I’m interpreting.

28. Setting it up for what we know I can right click to get a box that renames what I’m working with based on the names I want. (More useful for 3 person mixtures.) Also, I now have a running average for the proportions of the two contributors based on the 10 loci that auto-graphed.

29. Now we have to stop and think D3 is the first locus where our unknown foreign DNA type is not limited to one option. We have two options for the foreign type. Either a 15, 19 or a 19, 19. But compare the proportions to the running total and look at the phr.

30. Now we have to stop and think We’ll use the “Popout calls” button to work with this locus. We can now “click in” the alleles we want and the graph is adjusted in real time.

31. Now we have to stop and think As soon as we click the “19” box the results of a 19 homozygote and the known 14, 15 are added to the graph, and we see that this option, while meeting our required known profile (14, 15) and >50% phr conditions, doesn’t work because the foreign type is now a 30% minor contributor rather than the 65%(ish) major seen in the running average window.

32. Now we have to stop and think So we also click the 15 box for the foreign type, and see that this is a much better fit for this locus. (It’s still not perfect, as it’s a 1:1 ratio here, but...)

33. Now we have to stop and think Correcting for stutter improves things a bit, it’s no longer exactly a 1:1 ratio, but more to come…. (don’t expect miracles though)

34. Now we have to stop and think D7 again has a choice, but a 60/40 mixture with a major foreign type at 74% PHR is much better than the other choice with only a 54% PHR and a 34% minor type attributed to the foreign type.

35. Now we have to stop and think THO1 D13 and THO1 have the same type of choice between 2 options for the foreign type. D13

36. Now we have to stop and think D19 gives us three choices to choose between. But if we apply a minimum proportion of 7%, we would be left with only one type to choose from.

37. Now we have to stop and think D19 is a two allele pattern, and since we’re not concerned about the foreign type dropping out, and we don’t think the foreign type went from a 60%+ major to a 6% or less minor, we can choose a 14, 15 type for the foreign type. But notice D19 didn’t graph, as we have both contributors sharing a type, so any proportion would be completely arbitrary. (And wrong.) Also, Amelogenin didn’t graph.

38. Final results We can now do a match of the Victim reference in the original table to the mixture interpretation table and see that we deconvoluted an exact match to the Victim’s reference. We can now do a simple single source RMP calculation

39. Single source RMP stat I can send the deconvoluted profile to the single source stat page and get a value of 1 in 313 Quintillion. Due to screen shot limitations, you can only see a few loci in this view.

40. But that ugly graph… Did anyone notice that our graph is kind of ugly? The proportions jump around all over the place. Does this mean we are incorrect in our interpretation? We can rearrange the graph from large loci to small loci to see if there is a smooth change across the sizes of the alleles. – This is great to track degraded DNA.

41. But that ugly graph… This improves things quite a bit, and shows that the foreign DNA profile degrades some. But note that D3 is still a bit of an outlier. That happens from time to time. There is a wide gap between alleles at D3.

42. Another view of the graph You may prefer the graph to have the contributors stacked rather than plotted side by side.