Maths Behind Murder

This story happened in an Indian university. It was an unpleasant morning that day as the peaceful atmosphere was experiencing the sounds of police jeeps in campus and the faculty apartment building was filled with police. It was on February 02^nd, 2001, a murder took place on 2^nd floor, room no.2, with a note “PF” written by murderer.

After that one month has passed, and on 03^rd March, second murder on 3^rd floor, room no.3, with a note “PF” written by murderer. As all the victims are math professors, the investigation officers noticed a pattern in murder date, month, floor and room no. And they expected a murder on 04^th April, 4^th floor, room no.4. And all the police have made arrangements to catch the murderer red-handedly, but there was no murder on that day. All left home.

After one month, 05^th May, 5^th floor, room no.5, third murder took place with the same note left beside the dead body (another math Prof). There comes a person Ravi, a PhD student in math department to help the officers in investigating. Ravi notices the pattern in date, month, floor no and room no (2-2-2-2; 3-3-3-3; 5-5-5-5) of three murders, and carefully note “PF”, he concludes that murderer is following “prime factors” pattern (PF is the clue left by murderer), as 2, 3, and 5 are primes. As the previous three murders were happened in Feb, March and May, police are expecting the murder on 07^th July, 07^th floor, room no.7. So, they made arrangements (meanwhile prof. in that room was relocated) to catch him red-handedly, however nothing happened.

But after one day, police got a call from faculty building reporting fourth murder. It took place on 08^th July, 7^th floor, room no:8, with a note “PF”. Everyone was shocked, and unable to find pattern in murders to track murderer. And police gets a call from Ravi and they meet Ravi in CCD where he reveals an interesting pattern of murders while having coffee. Now all the four murders date, month, floor no, and room no are 2-2-2-2, 3-3-3-3, 5-5-5-5; 8-7-7-8. He reveals that murderer is not following prime factor pattern but the pattern is “Prime & Fibonacci”. Murderer is choosing month and floor no. as prime number, and choosing date and room no. as Fibonacci number. And that’s what the note “PF” left by murderer justifies. A Fibonacci number is a number which is sum of previous two numbers. So here, (2 3 5 8……..) is the Fibonacci sequence. So finally police think that, next time they can catch the murderer red-handedly. And by following pattern the next murder should take place on 13^th Nov, 11^th floor, room no:13. (13-11-11-13). Here Fibonacci number 13 comes by adding its previous two murder dates (Fibonacci sequence 2,3,5,8………), and prime number is 11 (prime sequence 2,3,5,7,11…………..). 

As the police are eagerly waiting for that day (13^th Nov), Ravi was not satisfied with the patterns he observed, and one evening in library, he was getting issued of books by a staff namely Trivedi (out of love, people call him Trivedi Uncle) who is working from last 30 years in the library and about to be retired soon. Then Ravi is so confused and puzzled with the word “PF”. And he was murmuring the word “PF” several times on his lips. And when he was about to take books from Trivedi, Trivedi heard the word “PF” and laughed. Ravi with a confusion and innocence asked Trivedi that what happened uncle? Then uncle said him that 20 years back, there was an exceptional and talented Ph.D student (namely Murugan) in math department whom people use to call “PF” (Psycho fellow), as he started behaving so. And also he revealed that Murugan was the friend/batchmate of current math professors (who are victims now) of our university, where his friends became professors now but no one knows what happened to Murugan.

And after some months, finally the day (13^th Nov) has come to catch him in 11^th floor and room no:13. Everyone is eagerly waiting for him suddenly some staff from guest rooms of faculty building came to police and reported about fifth murder in guest room, with a diary left beside the dead body.

With a pin drop silence all of them sat down and started reading the diary. And the words in dairy go as follows.

 “I am Murugan, and I felt blessed when I got PhD admission in such a reputed university. I entered into campus 20 years back (1981) with so many hopes and dreams like everyone. But I never expected that my dreams will become ashes so soon. I had 5 good friends who were doing PhD with me in maths department. As I had a personal connection with math, I use to explore math very deeply. I use to write down all the novel results in my personal book as computers were not widely used. There came a notification from ‘Clay mathematical Institute’ that a 100 year old math problem, whoever solves that will be awarded field medal with a cash prize of 10,000$. It has ignited a spark in me, day and night I worked and by God’s grace I have solved that problem and noted down in my book. My 5 friends copied my results and they presented that to Prof., and he believed that those 5 students have done a great work. Without knowing this, after 1 week I went and met my Prof and presented my work, and suddenly his face became red and angry and scold me that I have copied from my friends. Being very strict in research ethics, my Prof. gave me the termination letter and kicked me out of the campus. That’s how my career, dreams became ashes. And later I got to know that these people were recognized with field medal for that work. And regarding murders, I didn’t follow any prime-factor or prime-Fibonacci pattern. I was just taking revenge on those five. It is they (4 out of 5 victims) who followed pattern in choosing rooms while institute allotted them rooms in faculty building when they joined here. And the fifth one was newly joined prof, and as there was no vacancy in faculty apartment, temporarily he was allotted room in guest room.