Officer Gharty's attorney claims it's possible he did radio for backup but his transmission was blocked by another officer transmitting simultaneously on the same frequency. This is certainly possible, if two radios are transmitting on the same frequency, at the same time, the stronger signal will cancel out the weaker one, dispatch will only hear the transmission of the radio closest to them. However that would not be an acceptable explanation/justification for him not radioing for backup in the 30 minute window. Police are well aware of this possibility, proper procedure is for them to radio for backup and if don't get a response after a few attempts they are supposed to change to a different frequency. Police dispatchers operate on multiple frequencies for this very reason.