“Whether the knife falls on the melon or the melon on the knife, the melon suffers” – African Proverb


On July 6, 2015, Haverhill, New Hampshire police officers Ryan Jarvis and Greg Collins responded to a traffic accident on Route 302 near Bath. Dispatch informed them that the scene could not be secured as there was a man “armed with a knife” present.

The below is a redacted video of the event:



As Jarvis and Collins arrive on scene they observe a man walking along 302 with a large blood stain on his shirt, carrying a knife. The man is later identified as 41-year-old Hagen Esty-Lennon, and it’s noted in his autopsy that the blood was from a self-inflicted knife wound.

The officers leave their vehicles and approach him on foot. As they confront him, he reaches in his pocket and produces a blade. At this point both officers draw their duty weapons and issue commands to drop the knife. Failing to comply, he turns and begins to flee, then doubles back and charges Officer Collins – distance is hard to determine from the video, but it looks well within 21’. Both officers open fire, killing Lennon.

Lessons and comments:

– When viewing the single angle of Collins’ camera, we don’t see him produce a Taser, but it is seen on Jarvis’ and the dashcam videos. This probably had little to do directly with the investigation, but it should serve as a reminder to all of us that bodycams do not capture all the facts of an incident. Even multiple camera angles can still leave us with only a partial view.

– We make a habit of introducing all of our Force-on-Force students to the Tueller Drill. In 1983, Salt Lake City Police Officer Dennis Tueller produced data which concluded that an assailant armed with a knife, standing 21-feet away, could charge and stab a defender before they could draw a gun and shoot. This is also known as ‘The Teuller Principle.”

[Link to his original published article below]

The officers were faced with a textbook Tueller Drill, and in my opinion could not have handled it any better.

– People willing to take their own life are often not afraid to take others with them. Suicidal people are extremely dangerous!

– It’s in all of our best interest to remember that a) everything we do is being filmed, and b) film does not necessarily tell the whole story.

It’s on all of us who carry defensive firearms, serve on juries, or vote, to be eternal students. Keep learning!


“Natural selection will not remove ignorance from future generations.” – Richard Dawkins



Atty General’s Report on the incident.

Original Tueller Principle article