Any way to access log file on signed builds or without using Unity?

Hi,
Im trying to track down a hard to reproduce intermittent crash. In some cases it seem almost reliable, in any case where I can access the log file it is very hard to reproduce. I can access log files when I have just built from unity to the device with local debug token (using the unity interface to get the log file) but Im hazy about how to get it in any other case. I have tried intercepting log messages and saving them to another file which persists, but I have a suspicion the genuine log file gets one last message with a stack trace that this method does not.

Any suggestions or other tools I should consider?