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(copy) How Julie Brookes' Killer Gave Themself Away

by Jacob Reising


How Julie Brookes' Killer Gave Themself Away
The Science of Chromatography
By Jacob Reising
***Note: the following story contains graphic content that should only be viewed by mature audiences.
Background Information
Crime Scene Details
An unnamed but infamous serial killer murdered their last victim Julie Brookes on 9/23/21. Julie was home alone cooking in her kitchen when her killer attacked her, forcing a homogeneous mixture of pure substances. The liquid alone, made up of compounds and elements, was and harmless, but can be deadly because of its reactivity to saliva, which is a chemical property. When the liquid entered her mouth, it mixed with her saliva. This caused a chemical change that created a lethal substance with a low density. Because of the low density, it spread quickly in Julie's mouth making it impossible to spit out before her killer forcefully rubbed her throat, causing a swallowing reaction. She was found deceased with foam in and around her mouth as well as in the esophagus and stomach. Her body temperature was 74 degrees Fahrenheit, meaning that her body was found long after the crime.
How Suspects Were Determined
Pictures of the markers; from left to right Sharpie, Crayola, Expo.
Picture of Crime Scene (after body was transported for autopsy)
A cup of orange markers, whose inks look similar to the note, was found in the house, and fingerprints were checked. The following fingerprints, other than Julie, were from Michael Brookes, her brother, Paul Humby, her coworker, and Hallie Parker, her neighbor down the street.
Suspects Profiles
***No alibis could be confirmed because all suspects were alone.
Michael Brookes
-Reclusive personality
-Claims to have used the Sharpie marker when he came over to sign a card for their father a week or so back
-Claims to have been at the store, without buying anything, during the time of the crime
***Interview Notes: answers were vague, seemed withdrawn, seemed to want to get out of the room
Paul Humby
-Coworker, works part-time
-Known to be flaky to others' plans
-Claims to have borrowed the Expo marker at work a few days ago
-Claims to have been taking a walk around his neighborhood during the time of the crime
***Interview Notes: acted very calm about incident, answered quickly
Hallie Parker
-Neighbor that lives down the street, seems off- possibly mentally ill
-Lives alone but family checks on her often
-Claims Julie invited her over for lunch earlier that week, Julie recommended a restaurant and Hallie wrote it down with the Crayola marker (says it was a very pretty color)
-Claims to have been at home during the time of the crime
***Interview Notes: seems off- possibly mentally ill, dramatic emotions
Solving the Case
How Chromatography Works
Chromatography causes a physical change that separates substances using their physical properties, whether it be polarity, pliability, magnetism, etc. There are many forms of chromatography that can be used in many scenarios. In this case, it was used to separate inks and compare the results to determine who wrote the note. Forensic scientists used the "like" dissolves "like" principle to understand the inks reaction polarity of water and the non-polarity of the acetone.
The scientists used two solvents: water, which is very polar, and acetone, which is very non-polar. The most polar pigments rose the highest with water but the lowest in the acetone, and vice versa. The marker’s ink, which is a heterogeneous mixture, separated due to the difference in polarity in the red and yellow ink. The results differed from each brand of marker because of the different matter composition.
Results of Chromatography: Suspects' Markers
Official Conclusion
These results of the note's ink very closely match the Expo marker, the marker with Paul Humby's finger prints.
Side Note: Julie was the first victim of the lethal mixture, which Humby had created from various drugs that he collected from the veterinary hospital.
The serial killer who murdered Julie Brookes was, in fact, Paul Humby. Paul worked at a veterinary hospital as Julie's assistant, and was jealous that most of the patient owners talked to her more. He had called in sick that day, so that he wouldn't have a time stamp to suggest him as the killer. He stalked Julie home from work, and after waiting about two hours, he knocked on the door and she let him in. Paul followed her to the kitchen and attacked her.
After interrogating Humby, police found that the motives for his other several killings were that the victims had wronged him in some way. One victim had flipped him off in traffic, another had taken the last of an item at the store, and another had a dog that barked loudly and often. Since Paul only worked part-time, he had plenty time to organize and carry out these murders, without having time stamps to make him suspicious. Also, he used different tactics for each killing. So, the lack of a strong motive, lack of time stamps, and the varied killing techniques, investigators had very little reason to suspect Humby.