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The Case of the Fatal Frustum
Kenneth Russell, Professor Emeritus, MIT -- Design News, April 28, 2008
Urban Americans fear home intruders. The motive for the intrusion is most likely burglary, but the results can be horrific. A noisy dog, even of the Toy breed, is the best intruder repellent. Many urbanites do not own dogs and must resort to inanimate means.
Burglar alarms are a popular, if pricey, option. Some of these alert the residents of an unwanted presence, call the police and set off sirens and lights. The uproar is designed to cause the intruder to flee.
Dogs and alarm systems make sense mostly for homeowners. Apartment renters mostly rely on locks. But, there are locks and there are locks. Wikipedia reports on one urban crime study that found, “From victim interviews, we learned that in 87 percent of the break-ins that occurred when intruders defeated locked doors with tools such as screwdrivers or crowbars, the burglars targeted the one door that had no dead bolt lock.”
The Scene of the Crime
The current case occurred in a decaying city north of Boston. An apartment fire, obviously caused by arson, resulted in the deaths of an entire family. Forced entry was suspected. I was retained by the attorney for the interests of the deceased to investigate the door lock. He was suing the supplier of the lock.
The Investigation
I examined the lock at the Boston Police Station. The lock extended about an inch from the outer surface of the door. The protruding part of the lock was covered by the frustum of a cone, a tapered cylindrical shell that was held in place by dogs that hooked into the body of the lock.
With the frustum in place, the lock could only be released by a key. I was asked to determine if the frustum had been jimmied off to gain access to the inner workings of the lock.
The Smoking Gun
My job was very easy. The underside of the frustum was dented, as by a prying screwdriver. Also, one of the dogs was damaged, as by forcible removal.
A police officer who witnessed my examination of the lock asked if it had been jimmied. My attorney-client nodded his assent to my answering the question. I said yes, which likely confirmed the officer's suspicions.
The lock was of the snap variety, as opposed to the dead bolt type mentioned earlier. Once the frustum was removed, the workings of the lock were exposed. It was a simple matter to insert the screwdriver and flip the bolt back. It took me a few minutes to figure the foregoing out. Someone familiar with the lock could have defeated it in a few seconds. It would have been just flip, flick and into the apartment.
Why was such a cheesy lock used? The apartment was apparently publicly built housing that used the cheapest stuff it could find. The inhabitants were probably glad to have a place to live and never thought of complaining about such a pitiful lock.
But why was the apartment torched? The family was Hispanic, but so were many other residents. Racial animosity was pretty well out. I limit my questions on my consulting cases lest it appear I am trying to find out how much money is involved to jack up my fee. Finally, my curiosity got the better of me and I asked my client about the motive. It was a simple case of mistaken identity. A cocaine dealer rented the apartment in the past. Someone unhappy with his drug dealing torched the apartment to kill him and killed an innocent family instead.
My deposition was taken but I never took the stand. The lock was so blatantly inadequate the lawyer probably got a substantial settlement.
| Author Information |
| Ken Russell (kenruss@mit.edu) is professor emeritus of Metallurgy and Nuclear Engineering at MIT. He specializes in physical metallurgy, forensic metallurgy and failure analysis. Cases presented here are drawn from his actual forensic files. |
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