On October 28, 1991, a bomb exploded at the Roslindale home of Thomas L. Shay (“Shay Sr.”), killing one Boston police officer and severely injuring another.
The prosecution case was that Alfred Trenkler had built the bomb at the behest Shay Sr.’s son (“Shay Jr.”), who wanted to kill his father in order to cash in on an insurance policy.
In fact, it seems far more likely the bomb was related to Shay Sr.’s legal disputes, Shay Sr. claimed his previous landlords were making threats on his life.
The case against Shay Jr. (who was convicted in a separate trial) and Trenkler was circumstantial. The government introduced a sales receipt for a toggle switch purchased in October 1991 at a Radio Shack store, however the jury never knew that the switch recovered at the scene was not a Radio Shack switch.