Recently I send a message to Criminal case support team to ask them about the highest rank any player can reach, they answered me that the last update in criminal case ranks was in March 2014.
The ranks as I received from them:
There are currently 17 Rank Ups and they occur when you reach the following Levels:
     "Level : Rank"
1 : Officer5 : Deputy12 : Detective20 : Corporal32 : Sergeant45 : Lieutenant60 : Captain75 : Major100 : Inspector125 : Lead Inspector150 : Commander175 : Deputy Chief200 : Commissioner250 : Sheriff300 : Ranger350 : Marshal400 : Senior Trooper
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