I've heard this term in a TV Show called "Law & Order S.V.U."
I don't quite the grasp on it's meaning though at least to make it more simple and less legal so i can then translate it and explain it to someone who doesn't have legal terminology knowledge.
I found this on the web:
stitch-up noun [ C usually singular ]
uk /ˈstɪtʃ.ʌp/ us /ˈstɪtʃ.ʌp/ UK slang
"a situation in which someone is deliberately made to look guilty of doing something that they did not do"
But on other ones it says something different, so I'm in a pickle of what really is.
Could you forum gurus give us a little help?