I missed a few episodes but I can tell you a little.
She witnessed a gang shooting in the first episode and ever since they have been trying to protect her. Some gang members shot up her house where she lived with her Grandma (I think). One of the detectives wanted her to go into witness protection but there was no money for it.
I missed some of the next weeks and I have no idea what happened to Grandma. But somehow she was staying with another detective and the gang members found her there too. They broke in and tried to kill her but the the cop was one step ahead of them. She shot two of them and the rest fled. Finally the feds are taking it more seriously and she will get into witness protection after all.
ETA -- I re-read the OP and realized you probably know that whole back story and didn't need that much info. Sorry!