Again....
Scoggins tells you that "someone" got on the radio once the ambulance left and this "someone" grabbed the service revolver. Now who do you think that was?
"And then I got out of the cab and run down there; the ambulance had
already arrived by the time I got there, and they were in the process
of picking the man up, and they had done had him, was putting him on
the stretcher when I got there, and they put him in the ambulance and
took him away, and there was someone that got on the radio at that
time and they told him he was going to report it, so they told him to
get off the air, that it had already been reported, and he picks up
the officer's pistol that was laying on the ground, apparently fell
out of his holster when he fell, and says, "Come on, let's go see if
we can find him." -- WILLIAM SCOGGINS
Read it again.
The "someone that got on the radio" was Callaway and the "at that
time" was once the ambulance "took him away".