​
Suspect
Name & #
Tom
Jacob
Christina
Frank
Ann
Mary
Unknown
Pen #
1
2
3
4
5
6
???
Spot
Distance
4.2
4.3
4.3
4.5
4.4
4.4
4.3
Mobile
Phase
Distance
4.0
4.3
4.2
4.4
4.3
4.3
4.3
Rf Value
1.05
1.000
1.023
1.022
1.023
1.023
1.000
Good day, ladies and gentlemen of the jury, and the people of the court. I verily believe
that I have determined the identity of the chemistry grade book snatcher to be none other than
Jacob. This is because, after performing a routine method of forensic chemistry known as
chromatography, I have been able to prove that Jacob’s identity is quite literally written all over
this ransom note they left at the scene of the crime. You see, the criminal not only left at the
scene of the crime the aforementioned ransom note, but they made the grievous mistake of
additionally leaving me their pen as well! That very error is what allowed me to locate the
perpetrator here and identify them as Jacob, your honor. Adding on to this, I know that while all
six of these student aids have separately interacted with our chemistry teacher at some point in
the recent weeks, they all have one thing in common: They each always have their own stock of
pens as well, never writing with anything else. As I was therefore given the six confiscated pens,
from the students named here as Tom, Jacob, Christina, Frank, Ann, and Mary, I was able to
perform a chromatography test using these six students’ pens, as I had also separately already
done the same trial with the pen left at the crime scene. After a simple procedure of filling a glass
beaker with a small bit of 70% isopropyl alcohol, marking down a piece of chromatography
paper with dots from the six confiscated pens, and allowing the alcohol to run up the paper, this
allowed it to absorb and take the pigments found within the pens’ traces. Some time passed, but
as I observed the traveling ink, I noticed that several colors could be found leaking from the
traces, following the alcohol. Once the procedure was finished, I removed the paper and quickly
measured the distance traveled by the mobile phase, resulting from the alcohol running up the
paper, and then measured the distance traveled by the spot for each of the six pens. As I had
already done the same with the unknown’s pen sample, this allowed me to compare it to the six
marks. Almost instantly, I saw that the colors of the unknown, being yellow followed by orange,
then red, then purple, then blue, and then pink looked strangely similar, if not almost identical to
that of pen #2, which belongs to no one else but Jacob, your honor. Additionally, the distance
traveled by the spot, the mobile phase, and the Rf value all line up perfectly between the
perpetrator’s pen and Jacob’s pen. I believe I’ve presented enough to indict this criminal for his
actions, and therefore propose that he should be punished accordingly, your honor. Good day.