Source: vocabulary for the high school student by Harold LevineThe colonel has been a model officer. I can only guess that his superior was acting out of malice when he tried to demote him.
I know the meanings of each word in the whole sentence but I can't understand the whole meaning.
Let me tell you what makes me confused:
I don't know "was" refers to the time before being a model when he was a colonel or it (was) refers to the time after he started being a model officer.