Complex sentence: Realising that they could both be tested for taking drugs and charged they decide to cover up their mistake so they plant drugs in the house and place a firearm in the hand of Rainwood's unconscious body and they frame him as a drug dealer.
Split into simpler sentences: Realising that they could both be tested for taking drugs and charged they decide to cover up their mistake. They plant drugs in the house and place a firearm in the hand of Rainwood's unconscious body and they frame him as a drug dealer.