|I am reviewing for "I Write in 2020"
As a detective writer myself I was about to say this case was just too simple, then came the twist.
Plot and Characterisation
I'm not sure what your word limit was but maybe your detectives could have been developed a little further. I did get the character of the husband fairly well. The plot started simply but that ending came as a big surprise.
Spelling and Grammar
I spotted the odd typo, common mistakes when the muse takes you and you type at speed. Otherwise, no problems.
When the contest is over consider lengthening this piece. Give us more of the detectives, their appearance, their quirks. Let us see Jimmy at work. More importantly, let us learn a little more of the true killer, the guy behind the music.