How did Micco get propelled backwards hard enough to fall into the table? Doors typically open into rooms rather than outwards. Someone would have to burst through the door and push him. If someone else was there, pulling him backward would seem odd. Why not just hit him? You'd think Micco would catch a glimpse of the intruder.
As I thought, Sam was free with his alarm codes which doesn't narrow the suspect list.
People like Sam don't handle losing all their money well. It ends the constant party and tends to make them desperate. Now some may see his debt as a reason behind his death, but it's not an effective collection technique. It's only a motive if you're willing to write it off or if his death opens a new revenue stream.
I do wonder if Sam was trying to claw back some or all of the gnenerous donation to the refuge. Did he have life insurance?