I have never before been near a murder, but murder had been creeping up on me since I moved to Baltimore in 2013, so I suppose it was just a matter of time. As I told friends and family, at first I had an involuntary reaction — a nervous "What now?" chill — when I saw blue lights flashing behind me on the road. I had never seen so many cop sirens before moving here. Now I don't even flinch.
A few weeks ago, I was meeting some scientists at a Navy facility south of here, and the head of the group told me that he had seen someone shot right in front of him on the bus. The point of the story was to not take the bus.
I even lived in Jamaica, the tourist slogan of which — "Make It Jamaica, Again" — only works if you survive the prior visit (a Pakistan cricket team coach did not). Around the time I ended my year on the island, a lecturer at my university was found murdered in his own house, a few miles from mine.
Last week, murder struck home.
Alas, the stabbing of a Morgan State University student in my apartment complex, Morgan View, may not be big news in Baltimore, but the fact that it took place in what is essentially off-campus housing for college students may be newsworthy. And it may be an opportunity to give math the old college try to help solve a murder case.
I have been a consultant for the TV crime dramas "Elementary," "Numb3rs" and "Medium." And I was nearly a consultant for the film version of "The Oxford Murders" starring Elijah Wood; I knew the author of the math-themed murder mystery when I was a math graduate student at Oxford University. He said he wanted me to be the consultant for the film, and a producer contacted me to be a consultant, before he was cut out of the movie himself. But I don't just help fictional police.
I can't tell you about a meeting I had with the police department of a major American city a few weeks ago because I signed a non-disclosure agreement. Policeman Kevin Blake, an assistant commissioner of police and director of the National Intelligence Bureau of the Ministry of National Security in Jamaica also used my work to break up at least one criminal gang, according to the Jamaica Observer newspaper; Mr. Blake said "the application of mathematical theory in the effort to dismantle gangs" has led to "ground-breaking achievements" and that I laid the "pioneering foundational path" for it all. And I was once asked to speak to the Los Angeles Terrorism Early Warning Group; I connected the organizer of the group with Vladimir Keilis-Borok, an earthquake scientist at UCLA who had a model for predicting the number of homicides in Los Angeles. (Answer: a lot.)
So, how can cops use math to solve the murder in Morgan View? The stabbing occurred during a fight that police believe involved up to 20 people — students and non-students — after a Morgan basketball game. If two suspects are arrested, police can try to find others using the "small-worlds" idea from graph theory (the brain-child of my brother's calculus teacher at Harvard, Steve Strogatz), which suggests that if you have a friend, you are more likely to be friends with their friends. So police could look at mutual friends on, say, Facebook, or in phone records.
What they may not be doing is using software to find cliques — clusters of people all of whom know each other — in those Facebook accounts and phone records. The use of such software might be new. After all, a group of people fleeing an unplanned murder might send each other a flurry of messages via phone not to say anything. It's worth a shot.
Jonathan David Farley (www.latticetheory.net) is co-editor of "Mathematical Methods in Counterterrorism."