When forensic analyses are done single lane of a gel to

Last updated: 8/28/2023

When forensic analyses are done single lane of a gel to visualize all the different STR alleles sizes at once Then a laser is used to detect the position of the bands and all the results are read out into one graph as shown below for four different STRs The top image below labeled Allele ladder shows peaks corresponding to all possible alleles for all four markers which is why there are more than two peaks for 3 of the markers The numbers across the top show PCR product sizes in base pairs Numbers above each peak indicate STR allele numbers except for Amelogenin where X and Y indicate the alleles of this marker located on X and Y chromosomes respectively The labels below the graph are the names of the four STR markers analyzed here Amelogenin TH01 TPOX and CSF1P0 Below Allele ladder we see results for a crime scene sample Evidence Sample and for two suspects and one victim 100 120 XY 140 160 Allele ladder Amelogenin 5 Evidence Sample 180 7 TH01 Victim Reference Sample 200 899 3 Part 1 What conclusion can be drawn Suspect 1 Reference Sample Suspect 2 Reference Sample 10 220 240 678 10 13 Mik TPOX O Both suspects match the evidence sample O Suspect 1 matches the evidence sample O Suspect 2 matches the evidence sample O Nothing can be concluded 260 280 300 9 8 11 Mit CSF1PO 320 340 15