Murder in the Bronx

This is an article from Metro. In the article it explains how the case is still developing but the police have narrowed down a main suspect...the son! The woman was forty-five Tonya Bryd and her son, the lead suspect, twenty-three years old. The article described that the son called his mother in as missing but when the police came by to get a picture of her they smelled bleach and saw latex gloves in plain view. The police were in the process of obtaining a search warrant when one night a man walking his dog stumbled upon a bag that his dog would not stop sniffing and opened the suitcase to find human hands and shoulder. The man called the cops and they saw that the garbage sacks full of the body parts and the torso was wrapped in a shower curtain.  The son's alibi was that he left his mother either Sunday or Monday with her ex-boyfriend and his girlfriend and went to work. This whole story sounds like the son did it. He has the bleach, gloves, and not a solid alibi. He can't even remember the day he left them. His alibi smells fishy. I know that it probably is the son but it would be interesting if the killer was the ex-boyfriend. The part that I can't put together is the why. I see that the ex-boyfriend has the obvious motive of jealous ex-lover but maybe the son had a dispute with her prior or the mother got angry because she didn't like her son's girlfriend. I think the case might give surprising results since there are many possibilities. The case is still ongoing and will be updated when more facts arise. Who do you think did it? Why them?