Phone records are obtainable quite quickly in serious incidents (under 5 minutes re life and death issues)
Phone records for the incident in question can be obtained , the actual detail (number called or calling would not be disclosed) just the time of the calls / texts
Then the issue of time comes into it , ie their clock time may be different to the police officers time . Officers would check their timings with the speaking clock , the phone company would tell the officers asking for phone info how their clock timings relate to the speaking clock
Phone records convict many hundreds if not thousands of people every year (Crime not motoring offences) due to what infomation can be obtained from just phonecalls made or received