Forensic Science students began the spring semester by studying serology, focusing on Punnett squares and blood typing to understand how biological evidence can be analyzed in criminal investigations.

The lab introduced students to how forensic scientists examine biological remains at a crime scene and how that evidence is used to narrow down suspects. Students learned the difference between class evidence, such as blood type and individual evidence, such as DNA.

“When Forensics looks at biological material some of it is class evidence and other types like DNA is individual evidence,” forensic teacher Carol Seng said. “Punnett squares are a way for students to see how we get our genetic makeup and how we can eliminate or include people as suspects.”

During the lab, students study the ABO blood group system and the Rh factor. Working in pairs, students tested multiple known and unknown blood samples using Anti A, Anti B, and Anti D reagents to determine blood types. Senior Rachel Abraham said the lab helped clarify how genetics connects to forensic investigations. 

“We learned about the O, A, B and AB blood types,” Abraham said. “We used punnet squares to predict blood types by crossing each of the dad’s blood types with the mom’s blood type to find four possible outcomes.”

Seng explained that while blood typing is not as specific as DNA analysis, it is still valuable when DNA cannot be used. Students also practiced interpreting test results and learned how blood clumping reactions indicate the presence or absence of certain antigens. Compared to earlier labs, students found the serology unit more approachable. 

“I think this lab was easier than the hair lab,” Abraham said. “You had to be really precise with the hair lab.”

As the unit continues, students will build on their knowledge of biological evidence and move into more advanced DNA analysis techniques, further connecting genetics to real world forensic science. Students will perform the blood splatter lab in early February.