So you've already decided that Dez is guilty and the crack addict excon is telling the truth, and when he's not guilty it will only be because the crack addict ex con.
Wow, how convenient for you that you've positioned yourself this way.
Since you get to make up your own truth, here is how I think it likely played out. Dez is supporting his mom and paying for her house (how else is she paying rent?). He and his step brother stop by unannounced and finds his mother and another half brother high with drugs out in the open. Dez becomes irate and says he's cutting her off the money because he's not going to pay for their own personal drug den. and that he's got too much to lose to have that stuff in a house associated with him. He and the drug using step brother get into an altercation, and the mother gets in the middle and gets in his face. He grabs her and pushes her away. She calls the police out of spite that Dez has threatened to cut off the money with some incoherent story about about he "threw a ball" at her (which then later morphs into "ball cap" when the police arrive). The police come down and find no evidence of any domestic violence took place, and nothing comes of it. A couple of days later she calls Dez and threatens to file charges unless Dez agrees to put her back on the gravy train. Dez calls her bluff, and she goes to the magistrate with a new more coherent story this time, two welts on her wrist and *voila* an arrest warrant is issued, and Dez is tried and found guilty immediately in the court of public opinion before it even makes it to grand jury by people who REALLLLY desperately and inexplicably want Dez to be guilty of something. She continues to hold the charges over his head until he puts her back on the gravy train.
All just as feasible, if not more so, than "Dez just cold cocked his own beloved mother while she was knitting him a sweater vest and sipping on homemade lemonade" nonsense I've heard repeated non stop in this tread.