The money that the State Trooper took, although it was drug money, was not his. Taking money that does not belong to a person is punishable by the laws that are on the books. Accordingly, a State Trooper can be punished for taking money that does not belong to them regardless of the source of that money.
By taking seized drug money the State Trouper proved that he is no better than the drug dealers. This money was seized because it was illegally obtained, and it should have gone to the proper authorities. Taking something that does not belong to you is never acceptable and this State Trouper must be punished for the crime.
Although the State Trooper took money seized during a drug investigation, it does not give him the right to take the money for himself. As a member of the police, state troopers should all be held to rigorously high moral standards. This state trooper abused his power as an officer of the law, to benefit himself only. He should be punished for theft, because although he should know the law better than anyone, he still made the conscious mental decision to take the seized money for himself.
In the end, police are just as corrupt as everyone else in the world. The only difference is that they use their bade to protect themselves. With their badge, they hide crimes for each other, and give each other "law enforcement courtesy." They should learn that laws applies to them, too, but they never will, including the Trooper who took $70K in drug money.