There was possible icing conditions at the time, if ice builds up on the wings, the aircraft loses lift. There’s only one way it can go.
According to some aviation experts the most likely scenario is, he was configuring to land , had the autopilot on, started pulling back on the power while he was distracted by other tasks, was not watching his artificial horizon, the autopilot was struggling to keep altitude by raising the nose while under reduced power, he got slow, the plane stalled and the autopilot kick off when the stall occurred.
At that point he became a passenger. These slick high performance turbo props aren’t like a Piper cub, stall recover take a lot of altitude (which he did not have at 1600 AGL) . A ring camera in the neighborhood shows the stall/spin. He apparently tried to add power but by the time hid did it was all over. RIP. These slick planes require the pilots utmost attention. They are nit a Cherokee.
Runaway/frozen trim?